Jim;
Like every boat, the Hunter 170 had it's pros and cons. However I will disagree to much what has been said in this thread. First I am a retired Hunter dealer who introduced and probably sold the largest amount of these boats telling Hunter in many cases how to fix them.
Hunter entered into agreement with JY Boats owned by Dave Eck to get into the small boat market for a variety of reasons. 17 suggestions from me were incorporated into that design. However, I was not a fan of the ACP or plastic outer skin style boat but rather fiberglass. This is one suggestion not heeded. I learned a lot from Dave Eck.
The biggest issue is when the manufacturers changed forumualtion of the ACP materials without any notice to JY and later Hunter (Hunter bought out JY and later moved the company to Florida to a controlled environment) which caused cracking. When that happened, cracks could be seen, many of the boats being repairable. There were some that had to be replaced which Hunter did even after the warranty ran out. That was the biggest issue. THEREFORE, if the boat you are looking at has no cracks, then that is what I called one of the good boats to be considered. Just like any boat that has been hit hard, damage will occur.
With any daysailor of that size and weight, I never suggested it be on a mooring just due to the circumstances described above. This happened to others to include those manufactured by ComPac, Catalina, Precision and the list goes on as I used to sell them too. Therefore to say it was only Hunter is far from the truth. The suggestion about the mast ball being placed on top of the daysailors, as one of the largest if not the largest small boat dealer, I use to suggest them as standard equipment for all daysailors because even the experienced and novices when the boats would go over would prevent turtling or the mast going under just like with Hobie.
Most daysailors are more flat on the bottom of the hulls vs. V shaped. I am now speaking in layman's terms. The less wetted surface the better for sailing. Thus if heeling too much you had more wetted surface in the water thus slowing down a boat not to mention the safety issue and scaring the heck out of anyone going sailing with you. To end this, you sailed slower so the phrase from me, sail faster with less heel was suggested. In addition, I never suggested sailing any daysailor no more than 12-14 degree heel controlled by sail control and the amount of sail being used for the wind conditions. Thus my suggestion for roller furling jib being standard and I think one reef on the mainsail (cannot remember if that was standard) were incorporated suggested by me. This was true for the 170. In addition the experience level will always vary from sailor to sailor.
As for the motor mount, there is some truth to that. I never put anything over 2 hp on that boat and found the Honda 2hp standard shaft 15 or 20 inch shaft was sufficient as it had I think a forward/neutral /reverse handle vs. Tohatsu (makers of Nissan, Mariner and small Mercury engines as well) since those little engines had to be turned around vs. shifting which in some situations were dicy for those using the 170. However, larger engines and yes I have seen even a 9.9 being use were over rated for the boat or simply too much power for that motor mount would invariably cause failure of that mount. Then of course I have seen backing up too fast hitting the motor extremely hard for example on a dock. The motor mount for an overrated engine either too much power and/or weight caused much of the damage to them. So caution is urged on the motor should you buy the 170 and suggested is the Honda 2 hp with the lever control of F/N/R.
As for repairs, much has been said but I can help you on that. As for being designed as a racer, the intent was on a family oriented daysailor with a bigger cockpit so four could sit very comfortably. Yes you will get varying opinions but I go by knowledge and experience only when I respond to this forum. Feel free to contact me anytime by forum email.