Can I trust iTunes in the Cloud to retain past purchases?

Question

I've been using iTunes for several years now to download and watch television episodes, since long before the advent of iTunes in the Cloud, with its ability to re-download previously purchased music, television, and (most recently) movies. Prior to the advent of this service the iTunes user was solely responsible for retaining backups of purchases, although an additional download might be granted in case of catastrophe.
With this in mind, and as my collection quickly expanded beyond the threshold where I could reasonably back it up to optical media, I purchased a two-terabyte Network Attached Storage drive, configured in a RAID array for added redundancy. Unfortunately, my iTunes media library is now approaching one terabyte in size by itself, and along with the many other things that I store on the drive is beginning to approach the drive's capacity.
So, the iTunes in the Cloud thing sounds awesome, but I'd like to know more about the troubling caveat that 'previous purchases may be unavailable if they are no longer on the iTunes Store' before I jettison the bulk of my local media collection. I'm aware of, and can deal with, the reality that contractual obligations and other things may force the withdrawal of legacy iOS applications (Glyder 1/2, the Fighting Fantasy series, Zumocast), but am less able to suffer the unexpected loss of television series content that may represent hundreds of dollars of purchases.
Other media outlets like HBO Go and Netflix Instant Watch note if and when certain content may become unavailable in the future. Does iTunes have anything similar, or am I essentially flying blind if I choose to delete my media?

Answer 1

I would not delete the media unless you don't want it.
Even subtle changes to content listings can render thinsg unavailable.
I have several Music Videos I have never been able to upgrade to itunes Plus - they still seem to be in the store with identical running times, but itunes support claim they are somehow different and need to be purchased again - no chance.
I bought nearly 2 seasons of a Disney kids show - those sesons are no longer in the store as they've split each season into volumes (season 1 = volumes 1 and 2, season 2 = volumes 3 and 4).
For the sake of the cost of external storage these days I think it's well worth the hassle of keeping backups.
You could argue however that if 95% of stuff remains redownloadable is the cost of the 5% offset by the hassle/cost of keeping backups even if it 'changed' and had to be repurchased.
The trouble is we just don't know if it'll be 99%/1%, 95%/5%, 50%/50% in the future even if it looks favourable now. Movies frequently seem to flip from rental only to purchase only here in UK, not sure about elsewhere.
AC