If the thru hull is in a location where you are not going be stepping on it, or having to side-load it, then I think Marelon is fine. The Groco units work; however, you have to make sure you lubricate and work them more frequently.

My big concern will be the difference in the rough-in. If it's just the bedding, then you may be able to clean-it out and rebed the units; however, often they were installed with 5200 or some other very aggressive sealant. That keeps them in place and sealed -- until it doesn't, then I think it's tougher to clean-out and rebed over? Absent the, the easiest rough-in could be just replacing it with a matching Groco.