Hi Mark,
You may or may not remember me, we exchanged a PM last year when you first got your Z520 and I mentioned the 4 blade PowerTech prop Steve set me up with which I really like on my ETEC 250. Well my #2 piston blew on Pines 5 weeks ago, I should get her back from Rockwall Marine this week. I love the engine and have been just as impressed with it as yourself, however, I am thinking to get another boat with a Merc. My thoughts to sell are mainly due to the overwhelming negativity held against ETECs, mostly unwarranted, while I may still be able to get a decent sell for my 2011. On the fence post, love it, but this is also the first engine I've blown in 27 years of having boats..
I just traded in my 2010 Z520 with an ETEC for a 2013 Z520C with a SHO. Before you pull the trigger on the Merc come take a ride with me. I was considering the Merc also. The SHO will absolutely blow you away. There is no holeshot. It is either on plane or off plane. There is no in between. PM me if you want to take a ride.
Congrats on the new boat.