The 1.6 scene kind of skipped it, but Source had a ton of pro players who came over.
Players who came over? I'll list a bunch off the top of my head (not all good, but the best core CS has seen was 4/5ths Source players): shox, apEX, rpk, ex6tenz, KennyS, NBK, Guardian (technically played all versions), NAF, autimatic, friberg, fifflaren, dev1ce, xyp9x, glaive, dupreeh, pimp, adreN, anger, steel, DaZeD (a ton of American players were CSS, I can't even remember them all anymore) , the list goes on really...
You can't run and spray in Source and be accurate. The recoil is less than in 1.6 (and hitboxes larger), but you literally can't depend on running and spraying. The difference between 1.6 and Source here is that tagging was dramatically heavier in 1.6, and because of wall spam you can't quick peek a corner and then duck back, that's it.