But... with the new Version/Training: Do we really need Fast-Trainers?
I have some FT (old version, they gain ~110% at practice match) and nonFT (old version, they gain ~30-40% at p.m.). From the beginning of this season, I only use new Version. They all increase their skills pretty equal.
You have a point here.
This season, I had two powerful teams in my league - JUVENTUS and TANSIN.
This is a photo I kept in day 3 (day 1 of the league).
Of course it was impressing (even if I met those teams the last two seasons in CH.L. and League again).
When I saw the ages of the players, I thought, ok , at least they're not young so how much could the develop
Click image for larger version. 

Name:	JUVE TANSIN.jpg 
Views:	133 
Size:	71.8 KB 
ID:	67321

but know, near the end of the season, I can see that even the older players of Tansin, gain almost one star
JUNENTUS isn't so active (doesn't training much or watching his games) so the players didn't gain much.
Click image for larger version. 

Name:	JUVE TANSIN 2.jpg 
Views:	130 
Size:	76.6 KB 
ID:	67322


I also didn't make any power-training. I prefer to save my greens for the next season as I saw that it would be impossible to compete those two monsters.
Most of my players started as 5* - early 6* and gonna finish a high 6* players.
Willian, a 26 y.o. player (ex-fast trainer) didn't gain much even if he played in 30 games.
I just do the classic 6 drills pack (3 very easy and 3 easy in att/def/M&P, with -6,75 condition loss).
Day 3 - Day 24
Click image for larger version. 

Name:	TEAM D24.jpg 
Views:	131 
Size:	85.7 KB 
ID:	67323