To save time, could I get away with just using ProRes Proxy?

Question

Might be a dumb question.  But please play along with me...
I've been battling with FCP-X since it first came out.  Beach balls, crashes, failed auto saves, you name it.  Sluggishness is my middle name.  But I think it might be because I'm trying to force too much quality through my older, less powerful machines and my little firewire 400 hard drive.  All three of my Mac are 3-4 years old, all are from the old "Core 2 Duo" era (not quad core processors), and are all maxed out at 4GB of RAM.  While I've read that many people are having performance problems with FCP-X even on brand spankin' new suped-up Mac Pros with lots more horsepower than I'm running, I've long thought that my machines and their lack of power by today's standards may be at the heart of my sluggishness problem, especially given that most of the material I work with is shot in 1080 HD.  (I've never actually tested it in FCP-X, but I'm assuming that things would speed along more like I've been used to in the past if I would just do everything in Standard Definition 480, but that ain't gonna happen.)
Like many, I shoot most everything in 1080 HD (usually 24p, sometimes 30), unless I'm occasionally shooting 720 HD at 60i for later slowing down to slo-mo.
Here's my question:  Most everything I edit is for web delivery, and 99 percent of it is for my own use (not clients).  Mostly podcast-like stuff, although occasionally I'll create something for my business website.  Most of what I do is talking head type stuff, not a lot of motion (except for the 720/60i slo-mo stuff, which usually has some motion, which is why I shoot it at 60i for slowing down).  Most of what I shoot is green screen talking heads, intended to be keyed in front of some innocuous background like some of the generators in FCP-X.  I want it to look good.  Even great.  But given the limitations of power on my machines, I also don't want to invest an eternity in rendering and processing time.  The work I'm doing with video just isn't that important.  It's mostly for grins.
Until last night, I had been working exclusively in ProRes422 (aka "Optimized").  But last night I shot some footage and imported it into FCP-X, encoding it ONLY in ProRes Proxy.  And frankly, I couldn't discern any difference.  It looked every bit as good as the 422 stuff I'd shot before.  There was absolutely no difference to my naked eye.  That said, the footage I shot last night to test this out was not shot in front of the green screen (I'll test that out today or tonight), so maybe the Proxy footage won't key as well.  (I've been stunned at how good the keyer is in FCP-X, but up to this point I've only been keying ProRes422 footage, not Proxy.)  But really, based on just eyeballing the footage, I couldn't tell the difference between the Proxy footage and all the other footage I'd shot previously that had been imported and converted to "Optimized" ProRes422.
I'm not looking to deliver anything for broadcast television (if I were, I'd for sure use 422).  I'm not doing any feature film type stuff.  My video work consists mainly of stuff just for me, for my own personal amusement (and for the amusement of anyone who might watch it on the web).  It's intended for YouTube, Vimeo, or occasionally (in smaller dimensions than 1920x1080) for deployment on my company website.  Mostly, it's just me doing podcast-type stuff.  Occasionally I'll shoot and edit something for church, or for friends.  I like to think the production values of my stuff tend to be higher than, say, the footage Aunt Delores shot at Uncle Ralph's birthday party (okay, A LOT higher than that!).  But my stuff isn't going to air on "Good Morning Flatbush" either (unless, on the off chance it should happen to go viral).
So let me make my question as clear as possible:  Could I not get away with just using ProRes Proxy throughout my entire work flow, end to end, never switching over to ProRes 422 even when exporting?  Honestly, it has taken hours just to render the keyed green screen footage on a 15 minute video, and just the other night, it took the better part of 4 hours (after it was already rendered) to export a 15 minute ProRes422 sequence to YouTube (and then the darn thing timed out, essentially wasting all my time).  I'd rather just stay in Proxy the whole way through if doing so would streamline my workflow without compromising too much quality in the "look" of the video.  Based on my very limited use of Proxy (just testing it out last night for the first time), I couldn't tell the difference.  Maybe for web deployment, Proxy is all I really need.
Have any of you just stayed in Proxy the whole way through, never switching to 422 even when exporting?  Might this be an acceptable work flow for some of us, especially those of us on older, less powerful machines?  Is this a viable solution?  Do any of you work this way?  What's your level of satisfaction?
Thoughts?

Answer 1

A lot of what I'm shooting is being shot on a Canon XA-10.  Some (and certainly all of the 720 footage, but some of the 1080) is shot on a 7D.  And still more is shot on either an iPhone 4S, or even on a Flip Ultra (720p, 30fps).
Most is shot on the XA-10.
What I'm trying to avoid is the excessive render times (doesn't the ProRes 422 footage have to render as well?), and the ridiculously long times it takes to export.  Would all that not be reduced significantly by sticking to Proxy the whole way?  And what would the trade-off be?  I mean, I honestly can't see any discernible difference.  Maybe I will when I try to pull a decent key.  (Haven't gotten that far yet in my Proxy experimentation.)
Of course, editing in Proxy and outputting using 422 requires that FCP-X encode to BOTH when importing, right?  Doesn't that add yet another bit of time to the overall process?
I'm trying to streamline, and to reduce the overall amount of time I'm spending doing this stuff.