Fgarci I bought a jiggler set back when I was at the very beginning (haha that means like 3 months ago:D ) and I haven't found them really sueful. I often meet paracentric keyways, I think even the simple ones are paracentric here in Europe. The most common keyway I meet is the E1R para which already restricts the use of jigglers. (There are lots of very tight keyways here too.)
So there are very very few occasions when you can use them, but again, my experiences are very limited.
I mean in an ideal case they work well, but there are so very few of those ideal cases. Your money it much better spent on saving for a real good set of picks or maybe even on beer

.
(I'm just about to invest in some peterson picks. Not that I need them,of course, the locks I can't open won't open just because of peterson picks,
but I've been longing to try them for ever:) )
But don't let that let you down daniel22747, I'm sure you will find use for them:). I for one don1t have the southord jigglers, maybe they are better than the ones I have. I also don't know where you live, but as far as I know roomier keyways are a lot more common in the US.