Stakes shouldn't matter as long as you're playing within your bankroll - I like having 50 buy-ins for NL so if I have, say, a $1k roll then I'll only play at tables with a max buyin of $20. Maybe overtight for some but suits me and I've never gone bust following it

There is money to be made at both SnG and cash games, I think the best way to look at it is that you are not an SnG or a cash game player but you are a POKER player. If you want to sit for a couple of hours grinding out a cash game fine, if you want the adrenaline rush of the later stages of an SnG fine but don't pigeonhole yourself - specialisation is for ants!!