Yup, either cut the damn useless thing off, or if you want to keep the saddle in pristine condition then do it up "to keep the saddle flaps still" (and just why wouldn't they stay still??!). Don't do it too loose though, my friend has one and if I do it too loose it slips off the girth and rubs the horse. And they're a pain to do up once on (worse than girth). Oh sod it just cut it off!!
I've only got the Wintec Pro but that has the same strap thingy - with the lighter synthetic saddle it does stop the flap 'rucking up' if you bobble about a bit !! However I find it a pain if I need to tighten the girth once I am onboard... Have left mine on however.
I have one of these and although it is lovely and comfortable and I feel secure in trot it tips me forward so much I have difficulty riding in it. Anyone else have this problem?