just looking for thoughts, opinions? thinking of switching out dana marine for stainless?

they work fine.
did you upgrade the engine in any way?

Got a friend that is using them and loves them for a couple years now. I am using his left over Merc 496 exhaust cause I cant bring myself to spend the money.

SM makes great exhaust. Yet, it's not an upgrade over the DM setup. The SM has short individual runners in the manifolds that dump into the open riser. Your current DM setup has longer individual runners that don't dump until in the riser thru a merge collector. The DM is a much better setup IMO. Nothing to be gained going to SM other than a lighter wallet. CMI sport tubes would be the only exhaust upgrade over what you have now, and Bobl at FTM has dyno results showing only a handful more hp over The DM.

I have a stock 496 HO and just can't justify the $ spent for returns on upgrading the exhaust. I've maximized the stock exhaust setup by removing the turbulators and welding 3" stainless extensions onto the risers to within 1" of the tips. This way the water does not mix in until inside the tip. While no major difference, it can't hurt.