See my suspension weight thread, it gives a pretty good look at the differences when it comes to weight.

For me I went from webbing to whoopies, (thinking that I would save weight) but the frustration level of using them, made me turn back to webbing within in a year.

As far as a trees here in the PNW I ordered a "custom" set from Brandon at WB I asked him to make me some 20footers, and they work great. Haven't had an issue yet...Some times I do carry and "extender" kit which are 2 6ft whoopies, which I can use as part of the tree strap system so that the webbing can still go through the buckles.