Paulson,
I'm just saying what every other review, and reviewer has said before...When a new drive offers 50% better performance than drives that are only several months old (Barracuda IV, D740X), obviously it is going to get rave reviews. In reviews of the drive, you see comments like "breathtaking performance," "crushing performance," it "crushes the competition," etc.
But no, I don't own the 1200JB, but I do own two of the slightly slower 1000JB model. I bought them before I knew WD was going to offer a version of the 1200 model with 8Mb cache.

I did get them at a reasonable price though, about $180/ea. These replaced an 80Gb Maxtor D740X and 80Gb Seagate Barracuda IV....although I still use the latter in my work system (for silence).
Also, on a related note, when you buy a retail boxed 1200BB or 1000BB, you have a reasonable chance of getting the JB version with 8 megs of cache, as Western Digital stocks the boxes depending on their current inventory. A month or two back, Fry's had a huge inventory of retail 1200BB boxes on sale for $299 with a $100 rebate (=$199 total), and virtually all of these boxes actually contained 1200JB's.