I have the DM and my friend Eric (Mr.E on the forum) has the Two Brothers. They are very similar in tone, though I find the DM has a little more low-mid rumble and the Two Bros has a little more mid-high throat. The difference is very subtle at idle. DM is a bit more aggressive at higher revs. The DM is louder than the TwoBros. If you buy either one, I'd also buy some nice earplugs; I'd suggest
this variety pack, so you can figure out which ones you like and work for your ears.