A two part system will give a more professional, longer lasting finish...depending on the product it can be much more abrasion resistant as well...the down side..
1) Cost…
2) Two part products like Awlgrip are harder to apply however some, like Imron, are quite easy in comparison.
3) Greater health risk in breathing vapors or absorption thru skin.
4) If your boat already has two part Polyurethane on it you may be able to "go over" it with either paint system...but next time you paint you will more than likely have to strip off all the one part paint if you decided to go 2 part the next time. Check to see what the old paint system is on the boat now, as most two part systems will lift old oil or one part poly finishes and cause a unbelievable mess.

One part is for the Amateur who is trying to fool himself into thinking that he can get an Awlgrip like finish at an economy price…this is definitely one area where you “get what you pay for”.

Regards,
Bob