"Can I use your Double Gear Sling as a chest harness?"
Not recommended. I have used it like this once in hundreds of
pitches. I was horizontal under a roof and reaching for a blind
placement and it did help to keep my upper body from bending over
backwards. One time in 20 years on 10 feet of one pitch. If you
are a chest harness guy, you should buy a real chest harness/racking
sling.
"How strong are the racking loops?"
Very. The outer one is runner strength and the inner loop should
go to about 2500lbs.
"How comfy is the Double Gear Sling?"
Compared to regular gear slings, ultra comfy. Racks of 40 lbs
are not uncommon on big walls and having the Double Gear Sling
will make this no big deal.
"I'm a big guy. Is it going to fit
me?"
There is loads of adjustment available. Smaller people might have
a fit that is a bit big on them, but that should not affect comfort.
"Can I use the Double Gear Sling for
freeclimbing also?"
Sure. This is becoming more and more common.