Which high-end receiver?

If I'm not mistaken, the Macintosh is an analog multich channel preamp, right? If so, you can forget dynamics for movies. You're then relying on the processing in your dvd player and other sources, and your not getting the gain you need for proper dynamics and such..my experiences anyway...and that's a lot.
I could be wrong on the Macintosh, but I don't think so.
What speakers are you using anway? Makes a differnce.
Yes, receivers ARE NOT as good sounding as good separates, and usually not as strong overall, depending. In short, you'll have some compromises often.
Still, what has been recommended above, and what you're considering are, yes, the better receivers. Older 5.1's that sounded pretty good are Arcam's, Sony 777es, Nak AV10, Marantz SR14/18/etc, Denon 4802/5803/yada yada, Yamaha RXV1/DSPA1 and such.
Still, I find no "super receiver" that's going to replace good separates anytime soon. But you can do bass mananagement on these to help your power and dynamics, and at least get descent sound with the right piece, yes.
Might consdier the sunfire piece...heard it once and it did sound promising overall.

Actually the McIntosh is only analog for 2-channel stereo. It has full decoding capability for multichannel, of course.

Here is what their website says:

This MHT200 is a complete DTS/Dolby Digital/Dolby ProLogic 2 A/V package. With eight, 140 Watt Built-In power amplifiers, Infrared remote control, 24 bit DSP processing for Dolby Digital, DTS and Pro Logic, 7.1 Processing for expansion modes, 24 bit A to D and D to A converters (96kHz), 7 audio/video source selections with re-assignable naming, 6 assignable digital audio inputs (3 coaxial, 3 optical), and an 8 channel input for use with virtually any future external processors this is one product that you should be able to enjoy for many years!

Thanks for the input guys.

I have KEF Reference 205's for the left and right, and KEF Reference 202c for the center. The two rear channel speakers and two effects speakers are B&W in ceiling speakers (a concession to my wife).

Keith

Second B&K for the same reasons mentioned - true pre/power in one chassis, much like the Lex RV-8...but half the price. Have one driving 4 Paradigm Studio 100's and CC570. No problems.

Your equipment does not need to be located in the same room as your display. Apart from the DVD player you may not even loose any convenience since every front panel control is replicated on the remote and everything on the front panel display also goes to the monitor output.

Pulling wires into an unfinished basement or attic space can be done without cutting any more holes than you need for the wall plates.

Xantech makes good IR repeaters, speaker cable losses are not a problem out past silly long lengths (50' +), etc.