Merc uses clutch dogs in the Alpha, and Cone Clutches in the Bravo. VP uses Cones in everything. The VP gearcase is a bit larger than the Alpha case. Though the VP doesn't have the Raw Water pump in the outdrive, it isn't always easy to get at. You might have to cut a hole in the boat to get at it, or pull the engine, depending on how the boat is laid out.
I have used a VP SX for the last 17 years, and except for a Propshaft, it has been issue free. The Propshaft had to be replaced, not because of Defect, but because of an argument between some rocks and a Stainless Steel Prop. My engine is carbed ans uses a Mechanical Advance distributor, but has never been less than an almost instant start. Easy to troubleshoot and fix, compared to those EFI models