The imacasa pata de cuche looks pretty much like my larger truper, so far it hasn't worked so well with the underbrush...
I will put another vote in for the Imacassa. I purchased an 24" Imacasa Pata de Cuche from http://www.baryonyxknife.com and was very pleased with it. It has a distal taper (gets thinner towards the tip), which helps it whip through thin vegatation. The length saves my back and keeps me from getting too close to the thorny stuff. I also have a Tramantina 18" machete, but the Imacassa performs noticeably better.
Just my 2 cents.
PS. Be sure to put a good edge on it.