I don't think you find a week point. Players can play on NT very long, skills starts dropping at 33 (maybe slightly at 32), I think best players can play on NT up to his age of 35. If you look at our roster the oldest player is 28 (still training – last season 4 pops, we will see how many this season) and second one 26. Our NT is still quite young. To have about 20 great players you need average of 2 in every year starting from age 25 to 35.
i think that is the advantage of this philosophie, because it is easier for managers to obtain training them without the need of farms - but you still need enthusiastic managers for doing the off position training.
But at least when i could talk for me, i like to train multiskilled players like my PF, who probadly would fit your requirements ;)
@kareen: about the main skill with 32 no he wouldn't have them, because they cap earlier but i believe he won't be that far away because it isn't easy to train a 400k+ C, and also the cap works a bit into it. Personally this strategy could work, it isn't easy