If 4-on-4 is the solution then maybe we should be looking at the problem -- why is 5-on-5 so deficient?
IMHO 5-on-5 is *real* hockey and I love sudden death. The legs start going, the plays get more desperate and yes, 5-on-4 or 5-on-3 or 4-on-4 or whatever is exciting for a change (like a powerplay) but shouldn't become the status quo for overtime, just because we don't like the way 5-on-5 plays out. Maybe the problem is that the rules allow teams to play a crappy version of 5-on-5 (like basically playing 5 defensemen and waiting for an opponent mistake).
Maybe we should take even more pads off the goalies, maybe get rid of the instigator rule to allow skilled players more freedom, maybe get rid of the red line, maybe think about contraction so that we don't have so many mediocre teams compensating for lack of talent by playing some version of the neutral zone trap...
Do things that make 5-on-5 better.