Music Download Purchases: What level of Fidelity?

I am thinking of downloading some music and burning it, now that some of the music companies have started allowing me to pay for and register my ownership of the music. What bothers me is that I'll be paying for and downloading probably substandard files. They certainly do not appear to be of SACD or DVD-A 2-channel quality, which look to be the standards going forward.

Has anyone been able to nail down which Legal Music Download Services offer purchase-and-burn capability to music files that have decent or good sonic fidelity?
RealRhapsody uses CDA files, which I am told are not compressed files like mp3's.
Thanks, this will help me get some perspective on what they're offering. What's bugging me in part is that if I buy and build a library of music from them, then I will just have to pay full price again when I want SACD or DVD-A files. This is wrong... at that point I will have paid five or six or more times for some of those songs.

In the ideal (not that we'll get this.... just putting out there what I think the ideal would be), when I sign on and fully pay for a music service, what I would like are:

1. Full recorded (by them and me, or by a third-party) registration as owner of that which I buy.

2. The right to upgrade to better-quality-files, as they become available, without paying anything close to full (new) price.

I have spent a lot of money on music (vinyl, CDs, tapes)... much more than I've spent on equipment, and although I'm satisfied with many of the terms of those bargains (I can resell or rebuy vinyl and CDs in stores for example) there are other terms that I think should be renegotiated.

We music buyers should talk about what our terms are, as we continue to just go spending mucho money on our habit.
Another thing is, I've recently heard that there is some evidence that CD-R decays over some years, so that it is not permanent. So, at that point, if you did burn to CDs which decayed in, say, 10 years, so that some of them were going bad, you'd have to buy your music all over again. I'd rather be a registered owner with the right to re-download and burn if necessary, according to whatever terms agreed-to.

Were I a music company, I'd be worried about music getting passed-on, and copied, forever, so I'm not advocating those terms (I don't think) just that we have our rights set forth. I'm sure if you burned something and the disk decayed you'd be bummed.