Anyone using this ? Doesn't require heat but does heat help ?

Does it work over the long haul for bows

Look at West System G-Flex 650....super tough, shock absorbing, bonds dissimilar materials, one to one mix ratio. Great for bonding bow tip materials to each other and to the bow, grip overlays, etc. No heat source needed for curing. Use it for riser glue ups, tips, grip overlays, etc., and SmoothOn for lams.

I've been using the G2 for many years now without any failures. I only used it for limb laminations when I was building all wood bows, tri-lams etc. No particular reason, just a habit to use EA40 when laying up glass limbs.  G2 does not require heat, a 24 hr cure at room temp will work perfectly, but it cures with heat also.  It has a superior bond to oily woods like some of the exotics, and like the G-flex 650 that Richard mentions it is extremely strong and flexible and will bond almost anything. I mix it by weighing 100 to .40, so a bit of a hassle.  I use it for all riser laminations and overlays, and tip underlays, but use CA for tip and butt overlays. I never use heat to cure any riser layups, so taking a day for every step makes it a slower build but its worth it in the end.
Give it a try, you won't have any regrets. 

So EA 40 will work for everything we do in bow building. I can't figure out why you would want different glues when one will work.
My question is will the G2 work for everything and is it better than EA 40

No, I wouldn't say either is better, so you are totally correct in saying only one is required. The reason I use some G2 is because its readily available in many retail building supply stores in Canada at a very good price. I have to order the EA40 from Kenny or one of the other US suppliers, and after exchange, shipping, duties and taxes the product is about 75% more expensive.  I reserve the EA40 for my limbs because thats what I've always used, I have a lot of it in stock and I like the lower viscosity for spreading on lams.

How long is shelf life of the G2?

Can't say for sure Bue, the product I currently have is just over 2 years on my shelf.  I had some a few years ago that was left in my unheated shop over a long winter vacation, when I returned the resin was appearing a bit granular. I submerged it in warm water for several hours and it reconstituted to normal with no ill effects.  I have never had any problems with the product.

M&M i have winessed bows failing when not subjected to heat during glue-up. If you glue-up at 70Degs for example and shoot the bow at 90Deg plus theres a chance of delamination.

Been using G2 for years w/ no problems. In my own personal experience shelf life is 2+ years.
Reading the spec. sheets on different epoxies is educational.

I used a lot of systems 3 epoxy in boat building and its damn good epoxy. But using EA 40 is much more user friendly. But i'm not familiar with the G2.    Kirk

So I glued recurve up today with this stuff it mixed a spread exactly like ea40, I did put in the box @ 120 Fahrenheit I keep my shop @ 45 when I'm not in there putzing around and 60 when I am. Just a retired man trying to keep busy here, Thank God for real Craftsman bowyers I can purchase nice stuff from. This is the fourth bow I've made learn something every time.