Both headphones are torture devices stock. Especially after a few months of use. The pads get hard, they don't adjust to your head anymore and so can't seal. They functionally have no headband padding. I'd say they both are overpriced headphones, but the M50 even more so.
The 440 can reproduce bass, they were simply tuned by Shure as studio monitors, which means a steep roll-off bellow 100 Hz. To do this they simply chocked the drivers. You can remedy that in a few minutes in a customizable and reversible modification.
I would recommend the 440 in the condition that you are willing to hack them and invest some 30$ more down the road in new pads. The 840's pleather and 940's velour ear pads are much more comfortable than the stock 440's. Replacing the stock headband rubber with one of Sennheirser's headband pads will transform those headphones from torture devices to one of the most comfortable headphone ever. You don't have to do all this out of the box. I went a year with the stock ear pads before they cracked and fell apart, at which point I bought the better quality and more comfortable 940 ones. I waited another year before I scrapped the stock headband in favor of the HD650's headband pad. In retrospect, I should have done that a long time before.
As for the cups being shallow, this too can be fixed with a small piece of 1/4" Styrofoam.