I have been reading that a lot of guys replace the treble with a single hook. They do this for one reason or another but mostly because the treble makes it a little more difficult to get the fish off. I have not had a problem before but was curious if others have practiced this and if so does it affect the action of the bait?

Not "a lot of guys". Some guys for very specific applications.

I'm sure someone that does this will reply. I don't.

8-)

RW, nailed it, for some applications the single hook is great. I usually use a single on small crankbaits and especially in the fall when there are a lot of leaves in the water. Most often fish for smallies in shallow, rocky rivers and the single hook comes through cover better than the treble plus the fish is easier to release. Still experimenting with hook type and have not noticed any difference in hookups compared to trebles.

Wake baits over weeds is another situation where the single hook shines.

I mostly change the hooks on my spoons, single hooks for that application are referred to as siwash hooks and are made special.

IMO a bit harded to hook but once you have them hooked it's a more solid hookset and as mention much easier to dehook the fish.

I use a 2/0 perma plate hook on a 5/8 or 3/4 oz spoon

I replace all trebles on my spoons with one size larger single hooks. And I've been thinking about doing the same for hard jerks. If a smallie (or largemouth for that matter) hits an X-Rap, it really hits it usually! I do not see the advantage of the treble over a single hook in this case. If using trebles were any advantage, why wouldn't the pros be drop shotting with treble hooks?  

I've done it on a number of lure types, mostly to increase gap, make a bait more weedless (sometimes with home-made guard), make un-hooking easier, and damage fish less.

With crankbaits, I've tried it but not been satisfied -at least for the front hook. I have some that I've replaced the rear hook with a single. But mostly I've stayed with trebles but now mash the barbs down. This works surprisingly well for me. Keep the line taught during the fight and I've just not found a difference compared to barbed hooks -until I go to unhook the fish: Barbless hooks just slip right out beautifully. Lipless plugs I keep barbed though as they are seem easier for fish to throw.

If you are concerned about fighting fish with barbless hooks, there are micro-barbed hooks out there. Some Rapala plugs have them, and they are pretty easy to remove.