hi dg.
I have heard of it, and it is reviewed in this month's (Feb) issue of Motorcycle Consumer News. The reviewer tested it on a Honda ST1300, not exactly a Monster, but summed up his experience:
After road testing this product for a few days under a variety of riding conditions, I have come away impressed. The Tamer has transformed my bike from being demanding to ride to smoothly into nearly effortless.
At first I was worried that the slower initial throttle opening might cause a sluggish feel but am pleased to there is no such deficit. I wish I had discovered this nifty farkle earlier and, in fact, left wondering why the manufacturers don't similarly equip their bikes straight from the factory.In short they sound like they work well.
B and I are considering picking them up for our STs.
You could also try going down to a 14 tooth front sprocket. This is a very common mod to all Ducs to smooth them out at lower RPMs.
Good luck. [moto]