In early 2005, Euguene Karna of Conus Audio made a trip to mother Russia to bring back the last remaining 1500pcs of 6H30Pi-DR. He had pre-sold 700 of these, mostly to The Tube Store. The DR is a NOS tube; there are no replaceable lots. Since 2005 Eugene's haul has dribbled out and the tube gone up in price. In late 2004 - around the time the 6H30 was adopted by ARC to replace the 6922 - the DR varietal was going for $30 ea and today the price is ~ $175-$200+ a piece. The tube has been subject to some imprint misinformation and to counterfeiting.
Here is an interesting page on differences between the DR and the EB.
I don't believe there are any differences electrically between DR and EB of the same vintage; the DR went through more scrutinized testing for military use. Perhaps new manufactured EBs are not of the same standard but as far as I know both DR and EB are capable of a 7500-10000hr life span.
I've run DR, EB and cryo'ed EB versions in a variety of Conrad Johnson and Audio Research gear. The DR has a wee bit less grain, slightly improved top-end extension and slightly better focus. However, imo the difference is marginal - no where near the difference between, say, an Amperex 7308 vs a Telefunken. I love tube rolling but did not find the value in the DR premium. Usual caveats apply.