Of all the adapters I've had, I've only had issue with a couple.
What is your goal lumixdude?
Manual lenses can fill a couple needs very well:
1-Fast cheap glass
2-cheap Macro
So, priority is cheap
If you need wides, or zooms, you're better served within the system. Cheapest wide is the wide angle converter on the kit lens - that gives you a 20mm equivalent which is excellent.
If you really want speed, and want to cut back on the corp factor, I strongly suggest the focal reducer adapter I specified. EF mount will adapt many other mounts - nikon F, pentax K and m42, OM etc.
If you want to understand more on speed booster, here's a little light reading.
http://beomagi.blogspot.com/2014/01/focal-reducers-on-dslrs-and-light-gain.html
This is a test of a couple different solutions that all are 25mm F1.4
http://beomagi.blogspot.com/2014/02/a-little-test-of-4-different-25mm-f14.html
FD glass is good - my main lens WAS an FD, but FD is a little more restrictive in that FD glass wont work well anywhere else but on mirrorless. It limits the lens should you choose to spread out later and invest in another camera system, or sell the lens later since your possible buyers are more limited.
e.g. selling nikon manual prime will appeal to nikon and canon users since nikon F lenses adapt to canon EF mounts.
When you end up with a big collection of cheap (and not-so-cheap) manual glass, a focal reducer that adapts to most of them makes even more sense, especially when you look at F-Stop gain.
Browse through KEH. They've got some excellent deals. I'm buying lenses from them all the time when I see them for under $50 or so. One of my favorite wide angle 28mm lenses, is a tamron-F 28mm F2.8 I bought for $9.
Do note, I use this glass on my EP3 and 5D, so each lens is like 3 lenses to me...