personally Aerial I would stop for a moment, just take a step back, and stop wasting money. Do what I did, ASK people exactly what it is you need, and what they would suggest for you to buy. then and only then, spend the money.
Combining harnesses is certainly not something I would suggest. it is bound to be uncomfortable and they will have accelerated wear I should think. I only lasted a fortnight climbing in a rock harness before i upgraded to the real deal.
as has been said, Knots first, hardware second. tied correctly, the knots are foolproof, the hardware always has its quirks.
and as for how to bodythrust or footlock. They are both incredibly easy disciplines to learn, however hard to master.
just for point of comparison, to help show you that you're probably not affording yourself the kind of comfort and security that you should be, here is my 'beginner' climbing setup. compare how it looks similar to yours, but more importantly how it looks different
Jim
i realise theres a screwgate on there, but it is only used for hanging things onto my saddle etc. although theres some argument now that you should only affix a chainsaw with a triple locker too. nobody seen the petzl caritool then?
