Here is some comparison between M240 and M9 for a night photo made in Raw at ISO 200, 1250 and 3200 (2500 for M9 as it is the max).
Raw imported in LR 4.4 RC. White balanced to the same value. Some exposure decrease as photos were a little too bright. No sharpening.
Go here were I posted RAW files (better than jpeg for analysis).