After more research and discussions I removed the Boge Turbo Gas rear shocks and replaced them with KYB Gas-adjust. I was driven by the lack of local availability of the Bilstein Touring and also a recommendation from IPD for use with their overload springs on my 245.

When I pulled the Boges, the right shock had next to no damping for the first inch or so of travel. After that, further compression felt like a worn shock - resistance, but not a lot. Gas pressure was still evident, and the shock showed no sign of leakage. The left shock had damping over the full range of travel, but again it felt like it was worn out. These units were on the car for about 18 months and less than 40K miles.

So far the KYB's feel pretty stiff, but at least there's no more suspension 'crash' over things like speed bumps or RR tracks. My prior experience with KYB's was mixed - worked fabulously on an Opel 1900, but replaced 2 full sets (under warranty) on a Rabbit.