A slightly tongue in cheek comment which backfired because it hit chips on shoulders. Howls of northern outrage duly noted by someone who does indeed come from well north of Watford. Anyway, few London commuter trains have aircon. Oh you might get an Electrostar with it if you head further south, but then it's 3+2 seating...aircon consumes a lot of energy and is unreliable, and I'm sorry is only required in the British climate, anywhere in these islands, for a few weeks a year even in hot summers. Deep level tubes are another matter, but there it can't be done...
Pacers or their replacements should not be used for journeys of over 60-90 minutes. In fact they have largely turned into commuter trains, which was not the original intention.
The best is the enemy of the better. Gold plating requirements is one reason for fewer, more expensive and more overcrowded trains, and the survival of those monstrous 4 wheel carts way past when they should have died.
3+2 seating is more problematical. 2+2 more comfortable off peak, but more standing during the peak. I am cynical about the move from 3+2 to 2+2, it seems to be mainly so as to squeeze more in standing. Personally I would rather squeeze into a narrow seat than stand for 30-60 minutes.
As for power, we are talking about commuter and branch line trains, not 185's - even with hills, isn't 350 hp per vehicle adequate for a 75mph train? Would be interested to know how fuel costs rise with engine capacity, not linear if a bigger engine does not work as hard. As for 185's, 750 hp per vehicle does seem over the top. If (as should happen) the TPEs are converted to 4 cars, don't see why the extra carriage should need an engine.