Hi FrankF, my first post here at Audioholics although I signed up a while ago. Gee, what a tough predicament you're in...
The Dynaudio speakers are fantastic for music. For HT, which I find to be 100x easier, I could see them being deemed as overkill. +1 on SF Cremona's, but -1 on the PSB Platium. I believe better can be had for less here as far as Platinum; the value isn't as rich here as with their other lines such as the Images. In any case, I thought the T8's port overhang exhibiting common muddy bass was unforgivable, even in the context of the speaker doing very well in other arenas. Too many other good choices at that price point.
May I ask what kind of electronics you will have upstream? Something to consider is that if you succeed in spoiling yourself with Dynaudio's, they in turn will scream to be spoiled with nice sources, pre/pro, amp, etc ... don't blame them
Regarding the REL. Don't get them. Get the JL sub. I've heard the 305 at two stores, and the 505 at one, and I find them to be extremely musical and attractive. They blend very well, exhibited extremely even response during music auditions (of course much dependent on setup). However, they just don't cut it in the HT arena. At least that's how I felt about the 505 watching X-Men3. On top of that, the JL sub being much, much more adept with HT material, it is still also a decidedly better musical sub due to the extremely detailed transients it provides. I auditioned the JL with two sets of Dynaudio's, Contours and also with some huge Evidence towers (local JL dealer happens to exclusively sell Dynaudio speakers). Great match indeed. If interested, I can pm you with a good deal I found in TX (I live in CA. Local dealer wouldn't budge from msrp).
With that budget, you have so many options its scary. But perhaps you are relegated to the choices that your CI can provide, since I'm sure they should be giving you the best prices (or they better be !!!). If you are not constricted to your CI's choices, what else have you heard that you liked? Let's not put the cart before the horse, but you may want to consider room correction devices such as Audyssey and/or a SMS-1 bm unit with such a high-quality setup. More money perhaps...
I wish you the best of luck. I recently obtained my first high quality rig after an enormous amount of confusion and auditioning. Fun Fun Fun !