I can't speak for all other vendors but I'm stockpiling digis in my island volcano fortress in an effort to eventually drive the price up as they become "rarer", kind of like diamonds.
In truth though, montipora doesn't really show up on my lists as much as acros do now. I think the acros are more attractive and variable with the color combinations and a lot of the monties you see are the same things that have been around for years so demand hasn't grown like it has for other SPS. It's still out there, it's just that most people shy away because a nice green digi will most likely sit there in the tank while the acro colonies turnover more frequently. The ORA digis we have at Fauna grow enough to be fragged into several regular sized frags before even 1 sells.