Not only do you need to consider the motors, what drives?
Don't buy any boat with bravo 1's like I did. That's a mistake that is going to cost you more money down the road.

they both have XR's

I think Merc revised that down to 91 octane a 5 or 6 years ago, same time they did it for the 575s.

That said, go for the 500 and the newer boat if it's in good shape and is what you want. Get a leak down and compression check that will tell you a lot toward what needs to be done.

are you looking at the boat at GSC in morris?

the 525 sc is yesterdays news, go with the 500 efi.i had a pair os 525 sc 454s much more potentian with the 502 should you decide to upgrade later!

That's a good point . I still say who built the 525s if they were built right they do make HP. Mine have given me alot of trouble free hours.The budget is the thing . If he has the money to freshen the motors the 500s are the way to go. But when you open them up you just don't know . It could be a freshen up or total rebuild.I personally wouldn't run those 500s till they are refreshened they are time bombs.

X2 assuming ok leak down numbers. Plan on having the top ends of the engines done real soon.

lets say the guy with the 525sc, will go down to 75k, would you still go with the 500efi?
Also talk to a mercruiser tech and the valve spring issues is someting that they had an issues with the old carb HP500 and not the new 500efi, they use different springs

when i was shopping for a boat, i was hesitant about buying the one with the 525sc but it only has 10hrs on a complete rebuild with high end components. from what i read the 525sc will run trouble free with proper maintenance. my friend just had to have his 500's rebuilt and had some serious coin into them! can you swing the $20k in the next 2yrs to rebuild?

rebuild i would do myself in house.