very good. Almost back in the day ohlins good for their day when you could get them setup properly. Not rare for a lot of bikes because in additon to being sold aftermarket they came on nearly every twin shock sporting ducati starting with the later bevels (I think some later years of the Hailwood rep, 900SDS, Pantahs, etc) and well as really late triumph TSS and anniversary editions. I have a set that were originally mounted on my 900F that have traveled to a few bikes with me (another 900F, SOHC 750F). They need a rebuild at this point but they aren't leaking so that's a positive. The value in them is because they are cheap and easy to rebuild, so once you get the spring dialed in you never need to buy another pair of shocks.
They are excellent road shocks, not sure if I would use them to race in leiu of something more modern. For $500 NOS I can think of a lot of newer shocks I would rather have - aren't twin shock ohlins for a cb750 $550 brand new?