I have both leathermans that you mention, and I'm about to get the new swisstool spirit this week, so I'll let you know how it is. From what I've read on other reviews, the spirit will be similar to your swissarmy knives, they detent open and closed, but I don't have any personal experience with it.

But my experience with the Leathermans is that there's no problem getting the tools out. The wave has holes in the blade for one handed opening, the other tools are pretty easy also. Actually they're too easy and tend to fall out on their own, which is one of the reasons I don't like to use it. However, there could be some inconsistencies during manufacturing, so YMMV. One of the reasons I dislike leathermans is because they use non-adjustable fasteners holding the tools together, so you have no control on the tension, and there's a lot of variability from part to part. Unlike the SOG's which are easily adjustable with a hex head to the desired feel.

How old is your swiss army knife? If there is a lot of crud or rust in the mechanism it might cause some issues, but on a well maintained and clean knife I've never had a problem. The spring design is usually very consistent. Only on my really old knives did I have a problem, and a little oil usually helped a lot.