All I can say is that I don't have a horse in this race, and I'm a total gadget geek, and not even I can justify the time, cleaning, money and hassel of an o2 infustion system for my 5 gallon batches. Sanitation is binary. Either your beer gets infected or it doesn't. If your process keeps your beer infection free, moving to o2 infusion for sanitation purposes is a silly reason to do so.
"Good enough" is exactly that. Good enough. YMMV. This is just me talking about my brewing experience, nothing more.
I stir with a sanitized spoon, work the IC up and down through the wort and don't use an ice bath unless I'm brewing daytime and it's warm outside. Mostly I brew at night and the air temp is below pitching temp anyway. I get full boil 5 gallon batches to pitch temp in 15 minutes, then a couple minutes with my wingstirrer, and I can get to cleaning. My ferms go great, and my beer stays infection free. The pure science my indicate higher levels of 02 in the wort with infusion, but there's been some anectodal evidence from some very reputable brewers that it's not neccesary, and even some brewers feel it can potentially affect your flavor in a negative way. I don't know, because I haven't tried it, I haven't tried it because I don't NEED it to make good beer.
All IMHO.