I'm looking at some used 33-38' Formula's. Some are equipped with 454 Mags, 502 Mags, HP500's, or even 525SC's. I've heard the Mags called "Black" motors, and the others called "Blue" motors for obvious reasons.

I'm not hard on the throttle kinda guy. Don't get me wrong, I have my WOT moments! But, usually, I have the family with me and I contain myself to mostly cruising speeds (which I like between 40-50 MPH). I would hate to have a boat in which I would have to use the tabs to get me "on plane" quicker. So, I would like a powerplant in my next boat that would provide good "holeshot", mid-range acceleration and cruising speed. Top-speed is not a big concern, because I think that if I have the other 3 items mentioned above, top-speed should be around 65-70 MPH which is adequate.

Last, I need reliability and not have to worry about "teardowns" every 250-300 hours. Afterall, I am now in Florida, which means year round boating. I won't have winters in the garage to tinker with motors, etc. Now, tinkering time is sacrificing time on the water!

With all this said, am I better off staying away from the "Blue" motors or what?

All listed should be pretty reliable power.
The 454 is too small
502 Mag good choice
HP500 as long as it is an EFI....good choice..I like efi and so will your gas card.
525SC is a blower motor which I would tend to steer away from but still not bad.
Your reliability issues are most likely going to be drive related in a boat of that weight. The engine packages will be Bravo boats so look for the newer xr drives.
HP500efi w/ XR's is what I would look for out of the options you provided.

I haven't paid much attention to the newer stuff-until now. So forgive me for sounding stupid.

Other than the EFI vs carb, what is the difference between the HP500EFI and carb? I've heard that the HP500 requires valve jobs every 250 hours or so for proper maintenence. Otherwise, you run into spring failures. Is that right?

Did they do improvements to the EFI HP's to eliminate this kinda maintenence headache?

I know an OSO member with a very well kept 311 SR-1 with 502s.
I would make a move on it if I was ready.

He may have to sacrifice it.

PM me if you want more info. Not trying to do a classified here... just maybe connect two OSO folks.

i can help you with this problem

I think the 502 Mag is the most reliable engine Merc ever made. Jmho.

These are offshore boats we're talking about?????

The HP 500's w carbs had a lot of valve spring problems but I think if you fix it right once you're OK for another 400-500 IMO

Any of those motors will probably outlast a standard Bravo connected to it.

502 mag good, bravo one not so good. My alpha and 350 gave me less problems