I've putted on Insteps before, but not a lot and they're not bad for what they are. I believe there was one at the Sumner Meadows tourney a couple years ago, and I felt more confident in my putt sticking on that than in my Mach Lite. 3>2, indeed. The only thing that I'd be worried about is how well they'd hold up in the elements. The M-14's at Fircrest have held up pretty well, aside from some people bending a pole here and there. Also, dunno about the Insteps and putter shredding, but I have a stack of "Fircrest only" putters that I use, so you might need to factor in that cost as well.
Just to show that I'm not making shit up, this putter has only been used on M-14's. The gouge on the left was from one putt, the chunk on the right was from the last time I used it. Fine for practicing, but I keep my gamer discs sequestered.