Please Recommend 5 ch Amp that...

is around $2000 used or new, 120W-150W per channel, and
preferably THX certified and with balanced in.

currently looking at Bryston 9b-thx, and really want one of these, but seems to be little bit over my budget...
The little Krell Kav-500 has those features (I own one) and can be bought for less than your price.

OR, check this power-house out

I don't know if it has balanced inputs and needs 20A outlet but for the cost you could add a dedicated line and be under $2,000.

Theta Dreadnaught I/II?
I would recommend a used Bryston 9B-ST like you originally wanted. You could get one on Audiogon if you wait.

There is currently a cheap newly listed Brand New Aragon (newer version) that is 200x5, THX Ultra 2 for dirt cheap.

Theres lots of alternatives so its up to you.
I'm also thinking about the newer Bryston 150W 3B SST for fronts +120W 3channel 5B ST for center and rears

I guess, this way, 2 channel sound will definitely be better, but wondering if 5 channel movie or music performance will not be as good as getting 9B ST...

I guess, as alwasy, I will end up spend little bit more than my original budget... but I think Bryston is worth it for now and for long run...

...or you can check out the Proceed Amp 5 (or BPA/HPA).

The SST's are much better than the ST.
I like the McIntosh MC126 a lot. It is a little warmer than the Bryston and will definately be in for the long run. The MC206 is even better but it is (still) expensive.
Rotel RMB-1095
audio refinement
Much better sounding than Bryston and a mid-range quality that Bryston only wished it had.

240 watts at 4 ohms. Note: I do not Know the seller of these amps.

Arcam AV 300
Check Sherbourn 5 Channel Amp which have all these feature.
Used Aragon 8008x5 "under-rated" 200x5. Balanced, large 2.5kVA power transformer, 110 pound monster, retail $4200.