Air launching achieves what you want, higher initial launch altitude thus reducing fuel and potentially engine weight, with the added bonus of imparted initial speed.

My argument would be that if you're saving 5% efficiency (and cost) using something like air launching, which would get you faster and higher, the logistics costs of balloon launching would have to fit under that percentage to be desirable. For the design headaches alone, I'd pay the 5% and not have to worry about hanging a multi-ton rocket at 45degrees, under a slowly rising balloon.

I took 'improved payload to orbit' to mean efficiency, which would result in cheaper costs. Or improved payload size to orbit, in that you could take a slightly larger payload for the same fuel. Both being roughly equivalent anyway.

Your EM launcher is possible (someone attempted to launch satellites with a huge cannon during WW2 iirc), it has the same large requirements on structural integrity so is probably not overly suited to rockets. https://en.wikipedia.org/wiki/Space_gun It might give a little fuel saving if combined vertically with a normal launchpad launch though.

the balloon platform EyeR is referring to is toroidal, with the rocket coming up through the center. so no 45 degree rocket.

The center would be toroidial, and the majority of the lift would be sensible on a level plane, but some external heluim cell could provide more lift to one side than another and thusly provide for controllable tilt. You'd possibly not want 45° that low, maybe 15°.

Can't say I've seen any designs for toroidal launching balloons. I would've thought the risk of collision would be huge unless the radius was very large, requiring much larger attitude control systems. I'm sticking with my previous point; for the relatively low efficiency gain, I'd launch from the ground and save on design, logistics and risk.

For example, if the weather isn't conducive to launching on the ground, you just wait a couple days. If the weather turns bad after an hour of climbing to launch altitude, you now have to try to land the thing.

The idea was to generally get above things like weather.

Launch from ground is possibly a "better" overall solution, for mulitple reasons, but IMHO a baloon launch platform is a better idea than an elevator and could result in a reduced cost system for "light application".

If we're talking as an alternative to a space elevator, you're probably right; given time the logistic and safety problems might get ironed out and the efficiency savings would be worth it.

Not too disimilar to the model I'd had in head. Knew the concept was feasible. A bigger baloon system should be able to carry more - and with enough re-enforcement higher reducing fuel consumption.

But 600km is lamost enough to clear atomos - and if what was thrown that high had it's own propulsion system, it could in theory stabilise itself into a permenant orbit. A similar system might be a cost effective way to deliver ourselves a comsat network. minimal.

IMHO it'd be "more sensible" to devel our own launch systems. Maybe use theirs in the interim if we are in some sort of desperate rush for something.

Other people having already done such is only a good thing - it takes it from the realms of interwebs ramblings and sets it as confirmed physically possible. From here on out, it's just which way would be the "most sensible".

For some time the there was a firm believe, that the go-to material for space elevator would be carbon nanotubes ( http://mstnano.com/products/multi-walled-nanotubes/ ). However if there is any imperfection, this material gonna collapse quickly so there is still much to do there. Recently I have read amazing article about graphene being applied on spiders so they were making 30 times stronger silk. Maybe that would be material to go for.