I consider the DR260 the most common DSP on the market and the minimum DSP I'll use on any system. My monitor, front and side fill racks use them.
They've been dropping in price on ebay lately, they used to run around $600 but can now be had for 4~5 hundred.
I'll bet that Harmon hasn't changed or discontinued it because of it's popularity. I'll also speculate that as Harmon has consolidated brand manufacturing, their cost per unit has gone down over the years so their profit per unit has gone up. Why change a winning formula?