At PokerStars the 3,50$/7$ 50Fifty SNG´s are very soft without good Regs imo.
But I don't know the 15$ player pool.
I play these 50Fifty since April and my ITM goes better from 55% to 65%
But my sample size is very small. Just 30-50 Tournaments per month
After 189 50Fifty:
Profit - 136,46$
ITM - 63%
ROI - 19,21
But, as I already said, I'm not a grinder.
I work with ICMIZER and PokerTracker 4 (for HUD and notes). Both help a lot, because the player pool is not so big and you get a good hand sample size of your opponents very quick.
Greetings,
Christian