I bought the Leufken complete kit--with case. This has all of the components of the standalone kit, so I'll address those first.
* The water block is pretty nice. The bottom is good and shiny, but not perfectly flat (I lapped mine);
* The water bock clip is pretty poor--I had to bend mine to prevent the block from overlapping the chip socket.
* The radiator/fan combination is decent;
* The water tank has a pretty lame gasket that does not prevent leaks, in my experience;
* The pump seems to do the job, but it's a pretty cheap unit. I'll replace it before too long.
Overall I'd say it's a good deal for the money. The only real concern with the preceding is the pump--not sure how durable it is.
Now, I do *not* recommend that you buy the kit with the case! The case is way too small and is generally a piece of sh*t (screws everywhere--a real pain). It also has no intake fans and no good way to install enough fans to balance the air outake. I did a 120mm Panaflow blowhole, but who needs that aggravation. Also, the radiator/fan blocks the top 5 1/4" bay, so you will *not* have room for a CD-RW and a DVD drive. The case is so short that a second drive would strip cpacitors and/or fan headers from your mobo.
Unfortunately I can't give you any results, because my new main board arrived DOA and I'm waiting for a replacement.
Finally...Tom has been very responsive to e-mail questions, usually getting back to me within 4-5 hours. That's a big plus in my book.