My observations:
1) At NL10 the basic SSS is strong enough to generate a decent profit without any reads on any players at all. I played quite happily at ~5BB/100 for a decent sample without any stats just following the rules.
2) At NL25 it becomes a bit more tricky because the villains don't stack off as lightly. I find that with steals you can turn a small profit here without any stats but to really progress I would suggest playing less tables and using stats.
I think that it is possible to play a profitable strategy at NL25 without stats but why throw away one of the greatest advantages you can get?
It also depends on the site. The lesser known sites are generally fishier and will probably be easier to beat. I'm not really an expert in site-choice though.