I had a similar dilemma. I have HT2-TLs powered by an Ultra+ Double 550 and recently purchased an HT2C.
I ended up buying a used 260ex amp from Frank. I'm using 1 channel of it for around 190 watts if I remember correctly. Sounds great. I think I paid around $500 for it, and would much rather have an AVA amp than anything from outlaw or similarly priced emotiva.
If i were you, I would get the 400R since my main priority is 2 channel audio. I wouldn't compromise on that in order to have the front 3 channels on identical amps.
I'm currently using an eastern electric DAC, Ultra+ Preamp, Ultra+ double 550 amp, and salk HT2-TLs.
My dad is using an eastern electric DAC, Insight preamp, insight 260 amp, and salk Songtowers with the ribbon tweeter upgrade
His systems sounds very similar to mine when the low end extension of my speakers is ignored. His lacks some of the "magic" mine has, but it might not be worth the extra cost to some people. Every aspect of the sound is slightly improved on my system, but it's not a drastic difference.