For your ball-park comparison, I was getting one full + 5-6 BBs out of each mag with my Creation slide.
My new split-slide ones do almost 2 full mags. The "stock" springs are quite a lot stiffer than TM stocks however.
Ideally, without the barrel assembly in place, your slide should slide and "fall" out the front of your frame when you tilt the gun forward a bit (around 15 deg, really not much). That means the fit is loose enough not to slow down the cycle and use more gas.
99% of aftermarket/good quality slides NEED fitting to the frame to cycle properly. My favorite "technique" is to use whitening toothpaste. Remove everything from the frame except the rear-left midframe extension.
Use only the slide, no internals/BBU. Put lots of toothpaste everywhere that can contact and "play" with it for a while, preferably watching a movie or something that do not require your hands.
Originally Posted by Drake
Damnit, don't make me add "no discussing temporal paradoxes" to the rules or I'll go back in time and ban you last week.