I did a jumping kick on one at the fairground at last years billing show and it span round so many times the needle just jammed in place where it ended up, some big bloke came up a few minutes later and went to his little boy "watch how good daddy is at this" and had a go, the needle just twitched slightly and stayed where it was as it had jammed so badly, and he looked a proper cunt, it was fucking hilarious

Not sure if thats an issue on the digi ones or not though, but id imagine its equally possible for them to get damaged and start reading wrong, its like they are calibrated properly on a regular basis im sure, so I would think that comparing between different machines is totally pointless, even more so than 2 different sets of rollers.

Its definately true about technique though, my mate used to bounce at a bowling alley that had one, and by hitting it in the right place he could max it out with not much more than a big jab, where as blokes who im sure were hitting it a lot harder werent doing so.