Don't forget Xybots (I think that it used a different joystick than the rotating ones - I think you would just rotary-click once to the right or the left and then it would return to the center again but it basically works the same).
When I found out that you could use the original SNK LS-30 Ikari Warriors joysticks (the clicking rotary joysticks), I was all bent out of shape with excitement. I created a control panel and put those joysticks into it along with Druin's interface.
I was using the rotary joysticks for my main panel, but it turned out that the joysticks really sucked for Street Fighter II, or really any other game that required a non-rotary joystick (one solution to this might be to use the more expensive Happs version of the rotary joystick).
The other problem that I ran into is that even with Druin's interface, the controls were still kinda flawed. Mame treats those controls as analog devices, when really they were digital (12 position rotary or something). You could never get the analog settings perfectly right so that maybe 1 in 10 rotary clicks wouldn't register in Ikari Warriors. (Somebody at some point on this message board hacked some of the Mame drivers so that you could build mame yourself to process the controls perfectly... I have them somewhere if anyone needs them).
Lastly, after playing Ikari Warriors seemingly endlessly, I felt kinda let down. It's one of those Mame games that was pretty fun as a kid to pop in your only quarter and see how far you could get, but if you have unlimited quarters then there's really no fun in it at all (if you ask me).
So finally, I basically scrapped the whole thing. It's all sitting in the attic collecting dust (utill I can set up my cabinet to use rotating control panels, I guess.)
CONCLUSION:
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Using the SNK LS-30 joysticks with Mame involves a lot of work and a decent amount of money (Perhaps $100.00 for the joysticks and Druin's interface). The end product is only useful for a handful of games that I, personally, wouldn't call "worth it". Even then, (unless you use special, modified drivers and build Mame yourself) the controls are not quite 'arcade accurate'.
Using the Happs version of the joystick may make it possible to use the rotary joysticks perfectly for all the 8-way Mame games so that the one panel could be useful for most games, rotary or not.
By all means, if you have a cabinet with a swappable control panel, and you have a 4-player, Discs of Tron, Spinner, 4-way joystick, Defender, and a Steering Wheel control panel, then something is definetly missing: The rotary joystick panel. But as far as priorities go, I wouldn't put the Ikari Warriors panel higher than any of the rest of these panels.