First World Problem in need of Solution

@atownkeep I do not understand the concern about option 1 you have.

When you say "Sound is going to sound different from the rears and center than the front left and right
Thoughts: This seems like the best solution because my 2 channel listening will not be compromised" what you mean by "Sound is going to sound different?." 

Different compared to?. Don't you have room correction?. It should adjust the right / left SPL level due to the gain applied by your Luxman AMP?. Won't it?, apply HT bypass and calibrate then you are good.

Won't this work?.

I do not have room correction at this time despite several people telling me to download Dirac. 

My concern is that if I put a Yamaha, Onkyo, Marantz HT Integrated to power center and rears the sound produced by it will sound different than the the left and right speakers being powered via Luxman. 

Or if I went with separates with HT preamp and a 3 channel amp that again the sound would be different. 

I could be way off base and it may be fine. 

At this time I am thinking that buying two more M-900u one for the center and 1 for the back and pairing it with a Krell HT preamp may be the best way to go. However that is another 30k and I do not really want to drop that amount of coin for just HT. 30k buys a lot of trips to movie theater!

Or I am going to go 2.2 HT and just keep on rolling.  

Doesn’t your avr have distance or SPL setting per speaker ?. You could use that to compensate. I think at a crude level this is what room correction will automatically calibrate for you among other things perhaps.

atownkeep,

My Jeff Rowland 625 S2 amp drives my Monitor Audio PL500 II front speakers. My ATI AT523NC 3-channel amp drives my center and rears. I'm not doing "critical listening", so when I watch television or a movie I don't notice a significant difference. When I'm listening to music(2-channel) my ATI amp and AV preamp are turned off.

@ricred - I think those amps are relatively close in sonic signature.  They are not extremely warm and not extremely fast, but both pretty neutral.  If you had a radical mismatch, I think you would notice more differences.
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@atownkeep - I hear you.  I don't think trying to get a AVR Receiver or Integrated would really be the answer here, as they all have definite differences.  I think it's much better to look for a set of amplifiers that would closely match your Luxman amps.  Then the choice of HT Premp/Processor is not that critical, since all channels would be somewhat matching.  Since HT movies really need excitement, I would probably recommend a very high resolution HT Processor for your scenario.  The warm Luxman/other amps would sound too dull with a warm HT Processor such as Marantz or Bryston SP3 (yes, the SP3 is really laid back).  I am totally not a fan of room correction, although many other people are.  Both the Krell Foundation 4K and Anthem (either D2v 3D or AVM60) have their own auto-eq and room correction.  They are both high resolution processors and support 4K.  The Classe Sigma SSP Mk II is also a good high resolution 4K processor, but it does not have auto eq or room correctoin.

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That is kind of why I put forth the idea of getting a Parasound amp - it is on the warmish side, but still has good slam.  The A31 is probably a great price for a solution ($3200 retail).  Other amps could be like Aragon (they have both a Iridium monoblock a 8008 stereo).  Or something like a B&K, but they are very old.  I'm sure there are other warmish sounding amps.  You could try posting that question in the "Preamp/Amp" thread as "recommend an amplifier that sounds very close to Luxman 900u and offers both a monoblock and stereo amp".  The list of manufacturers that would offer a 3-channel which also has that warm sound is very small.

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Maybe an idea would be to pick/buy your HT Processor and then try a Parasound A31 amp from Audio Advisor.  They do have a 30-day return policy, so if it's not close enough sounding, you can return it.