[BajaMike]

I have a 3600 Open with Cummins QSB 5.9 engines, they are in my opinion the best engine made in that hp range, great dealer network for parts and capable mechanics.  They are quiet, very little smoke and are incredibly fuel efficient.  I regularly cruise at 26kt and am burning 26 gallons an hour, amazing.  The 3600 itself is a fantastic vessel, I've had it offshore in some nasty weather and she's performed, not a second of concern about the capabilities when things go from bad to worse with the weather.  If I'm to nit pick I'd say the hull rides a bit bow high, but I'm a short bastard and it's not a problem, more of an observation compared to a 43 Viking Open I've spent a lot of time on.  

I'm moving up and it's taken me about a year to come to terms with selling my 3600 Open, I will miss her, but the wife wants a flybridge, I'm not complaining.  I can't say enough good things about Tiara quality and the Cummins engine package, you can't go wrong.  However, as a previous poster pointed out, get a good mechanical surveyor and a strong hull surveyor, I encourage you to develop these relationships outside of the broker you are working with.  I've been burned, but only once, I've walked away from many more boats than I've purchased, the surveys are worth every penny.