The FSP has 40A on the 12V rails... very good. Can't find out how many combined amps the TT has, but the rails have 14A and 16A separately. Of the two, I'd go with the FSP. It's cheaper, good brand, and is quite capable.
If you must get one of the two, get the FSP. TR2 psus are v bad. Well, not bad exactly, they are solid as long as you stay within specs, but they provide very little 12V amperage compared to other psus with a similar total wattage rating. Hence the reason why they are so much cheaper than other thermaltakes.
TBA I think you should get the 450w, as it supplies 29A vs 25A for the 400W. Remember that a psus output drops over time, and oyu dont want it to fall below the needs of the system, especially since you may add another HDD or sometihng in the future, and you want to be prepared for it. Besides, they are both rather cheap, with only a small price difference.