I've kept mine in a slip 3 of the 4 summers I've had it. Each summer, I've taken it out at least once for a trip to a different lake.
My primary reason for going with the slip is that I do the entire thing solo, so that if I have to do the entire rigging every time, I am tired and sore before even getting started. I also feel like I put a lot of dings and dents in things while rigging ... This would be a very different situation if I knew I'd always have a competent helper with me.
As far as launching and reloading the trailer, I've never had any problems. I drive the boat on and off the trailer every time. This most recent time I loaded it, the lake was very low, so that I could not get the forward v-bunk under water at all; I just soaped that bunk up thoroughly with dish liquid and drove the boat in gently, left the engine pushing gently forward so the boat would not backslide, climbed down onto the trailer, and it took very little pressure from the winch rope to slide her comfortably right up into the "v".
Loading the boat onto the trailer in a cross wind can be very difficult. Most of us have extended the "goal posts" that Mac provides so that they are about 5 feet tall. In my case, since I solo, I added a second set of goal posts forward of the trailer wheels - even in a cross wind all I need to do is get the nose between the first set of posts, and then I can jockey her up and between the second set by letting the siderail bump on the goal posts.
For myself, the hardest thing about getting on and off the trailer is timing - I always try to be at the ramp at off times because I take a lot longer than most boats as I'm doing everything on my own.
There are those who say the Mac handles like a pig, but my opinion is more that it handles differently than other boats. With practice and after learning when to have board and rudders up or down, it is not that bad. It certainly handles better that the last "boat" I drove:
http://www.navsource.org/archives/09/59/09591001.jpg
- Andy