I have a set of the M-120s on my 1801 and it makes a huge difference in my ability to trim the boat in almost any kind of sea state. The feedback that I got is that the M-120s are more than you really need, but I like the quick response of the larger tab. No problem with clearance on the trailer, so I recommend the M-120.
I have the M80 tabs on my 1801 and they have made a world of difference. If I was doing it again, I would buy the M120 tabs for the extra surface area.