Apple ProRes - which version based on these edit requirements?

Question

Hi, first and foremost I do understand that the whole 'ProRes 422 vs ProRes 422(HQ)' debate has been covered many times in the past, so apologies in advance for digging this up once again! I've been reading up on this over the past week or so and I can't find any definitive answers specific to my issue, so I thought it was best to post it up on here.
I'm due to commence editing a short drama film soon which upon completion will feature on the festival circuit throughout next year, with a potential TV broadcast in the works too. We shot the film predominantly on a Canon5DmkIII and an FS700. I will be editing the project in FCP7.
My question here is that I'm a little unsure as to which codec to transcode the rushes to for the edit...all of the footage was shot 'flat' which means I'll need to do some extensive colour grading in post, as well as additional sharpening and denoising (Neat). Normally for my day-to-day editing which consists of mainly straight to web content I would transcode everything to ProRes422 or 422LT, which is obviously more than good enough when delivering the work online. Once again I'm considering converting everything to the standard ProRes422 codec, but due to the amount of grading/post work that needs performing and the fact that the film will be shown on potentially a cinema screen and on TV I'm wondering if converting to 422HQ is worth considering here based on the edit requirements and final output?
I mention the HQ codec in relation to its data/bit rate; meaning that as HQ has a higher data rate than the standard ProRes codec there's more 'head room' for retaining quality & detail after rendering the footage out and then exporting? Apologies if I'm wrong in thinking that but that's pretty much my enquiry in a nutshell there. I understand that converting to HQ initially will not give you a better quality file than the standard 422 codec (overkill in most cases), I'm just wondering if HQ (or any other codec for that matter) will retain it's quality better after some potentially heavy grading & filtering vs. codecs such as ProRes422. Storage space and render times are not a problem here, but I would only convert to a codec such as HQ if I know it's going to be worth it in the long run.
Any help/advice on this would be much appreciated. Thank you.
Alex

Answer 1

Unless you shot 12-bit RAW footage with the FS700 there's no reason to go to ProRes422 HQ. Your 5D mkIII footage (and probably the FS700 as well) is 8-bit and the standard ProRes 422 codec is 10-bit. Irrespective of how much work you do in Color (or the color grading system of your choice) the source will still be 8-bit, so 'headroom' is pretty much pointless.
hope this helps