I've done it but it is NOT pleasant. Much better / easier to pull motor...

Ha! Doing prudent due diligence about my purchase. Down to 38 TG and Fountain 38EC. The posts have been tremendously helpful!! I want the Cig, wifey pooh wants a cabin and shade, hence 38EC. Have had a 35 Executioner and a 22 Donzi. Moving up and want to make sure I have alll the facts. Hydro Hoist is where I'll store. Run on the Chesapeake Bay.

It all depends on the boat, but 99% of them are easier if you just pull them out. It will take damn near twice as long to do the job in the boat, thus offsetting the time to remove them. It also gives the owner the opportunity to address any other items like bilge pumps, clean and paint bilge, etc. IMO, you can do a better job with them on an engine stand rather than hanging upside down in the bilge.
Eddie

Amen!!!

Just talked to a friend of mine, hes picking up a clean 99 (i think) 47 Fountain, he knows the owner. Triple 500s, 500 hours each, never opened. He and I know the boat, clean, fresh water boat. all fluids and filters ontime.... Not dismantling anything said herein, just sharing. I guess I should ask the gurus, older 500s built "different/better" than 07 and newer 525s?

What year motors?
EFI or Carbs?
It matters.

What year motors?
EFI or Carbs?
I could assume 1999 and "HP500" carb motors, but want to confirm before suggesting anything.

Carb, I guess the old HP500 Bulldogs? late 90s

Now, a Bulldog is a different beast all together.

HP500 Carb: 502 block well optimized for 500 CSHP.
HP500 Bulldog (also carb): 540 block conservatively built for 500 CSHP; optimum build platform for blower motors back in the day.

But given what you speak of on age, I would be very surprised if they are performing well if the valve springs have never been replaced and an overall top end inspection. I would hope he had leak-down inspections done.

It's hard to compare the two but I'll stand by my assessment that there is no need to tear down the top end of a 525 at 200 hours unless it's a race boat. No disrespect meant to Eddie.