I would agree to combining the SUVs in one forum.
I sometimes post in the SL forum, and it's interesting to note that the month of August postings only occupied a single page! Obviously not much activity, given the SL models spanned as far back as the mid 70's! Conversely, you now have to traverse through two pages in the Tech forum just to get a single day's worth of posts!!!
I see maybe one or two ML posts every other day on the Tech forum, so I still don't think we need a dedicated forum. The ML has only been around since 98, so it will be a long while before the flurry of ML posts start taxing the server. Will the G-wagen folks share their space? Don't know.
How about it G-Wagen afficiandos?
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car