Well if you run games on normal TH you have to have the GPU power to do approx 4MP. Which is the same as a 30". I really don't get your point..if you can game on TH you can game on 30"
Oh and my TH is 5.3MP 'cos it is at 5040 and I have no probs with that. Admittedly I will have to update my GPU every year or so (8800GTX to GTX280 to next gen end of this year) but that is what you pay for the best gaming experience out.
However if you don't want to upgrade GPUs and are happy playing low settings on your TH and want to play high settings on single screen then I would say go for a 24" mon with speakers, if there are any? HDTVs are no good when you are close to them IME, they are great a normal viewing ranges but not monitor/PC ranges.
That is my point that with 8800gt oc sli, even on the th2g i cannot use the highest settings on many games. So i'd rather not have that on my single. Especially considering most of my gaming will be on th2g anyhow. Plus the cost of a 30" vesus a 27"/28" is not worth it when you take that into account.