ML ReQuests bi amp with 5ch amp? $1500 used?

First, thanks for your help. I've read many *excellent* posts. I hope I'm not asking a repeat question...

I have: L/R- Martin Logan ReQuests, C- ML Theater, Side- Sequel II, Rear- Aerius, sub- Velodyne HGS-18 (@60hz LFE+main), all driven via a Denon AVR 5803 for its video and processing power. As you all know, my ReQuests need a better amp, the other channels are fine, they are matrixed sound anyway (except possibly an amp for the center).

It seems that a high end 2ch amp, (250W@8/500W@4 $2000 used and up) is most recommended due to the low ohms and the ML power vacuum. I'm thinking of bi amping my ReQuests with 4ch of a 5ch amp vs. a quality 2ch. The thought is, due to bi amping, the top amp sees the panel's crazy impedance but lighter power requirements. The woofer (full range signal) is a more typical load. They both may possibly be served by a modest 5ch amp which is much cheaper than a quality 2ch. The obvious alternative is two modest 2ch amps which there are many. (suggestions welcomed)

I realize that auditioning an amp is best, but since I'm buying used, that is quite difficult. My budget is limited so I need 90% not the last few %. My use is 80% HT (family) and 20% 2ch for me in the sweet spot when they let me!

Any thoughts on the concept?
If practical, which 5ch amp for $1500 or less?

Some Examples: (alternatives welcomed)
Cinepro 2K-5 ($1400)
ATI 2505 ($1400)
Lexicon NT-412 ($1400)
Outlaw Audio 770 ($1400)
Sunfire Cinema Grand ($1300)
Sherbourn 5/5210 ($1300)
Rotel RMB 1095 ($1200)
B&K Reference 7250 MKII ($1200)
Parasound HCA-2205at ($1000)
Parasound HCA-1205 ($700)
Outlaw 750 ($750)
ATI 1504 ($600)

Please feel free to offer IMO (In My Opinion) and IALT (I Actually Listened To) comments about amps with any type of panels.

Thank you for your help.