What major effect does the lack of an infinite anti-reverse have. Is it something which is markedly noticable? No big deal?  Yes got to have it? Thanks!

Are you asking about an instant anti-reverse.  If so it means that you can reel in the line but whenever you stop reeling the line is tight, for an instant hookset.  There is no backplay in the handle or reel.  I have a Pflueger underspin that does not have instant anti reverse and there is always a possiblity of slack line which must be taken up before you can achieve a hookset.  You can remove the slack by reeling then setting the hook or by moving the rod far enough.  Personally, the lack of an instant anti reverse annoys me, especially because it is on a reel I use for Crappie and other light biting fish.  

Instant or infinite anti-reverse is nice, but I never viewed the other as a problem. How much backplay is there in the others? Maybe 1/8", if that? I can't know anything for sure, but I don't see how that can cause problems and I have just as much confidence in those reels as those with the infinite.

Between reels with and reels without "It is something which is markedly noticable?"

Tight Lines!!!!!  

Well. That pretty much anwsers my question. Thanks! Looks like I will stick to Shimano and fish on. I was considering a Daiwa SS but I might as well stick to newer technology and I like Shimano spinning reels.