I have both. They are very different mics. I prefer the ATM 25.
The ATM 25 has a better frequency response for drums. I find the ATM 250 better suited for smaller drums (not that I think it sounds better than the ATM 25). The bottom end is a bit too much for the bigger drums and the attack sound is not the same as the ATM 25.
Obviously, you'll need to try them both to decide. But to my ears, the ATM 25 is a superior mic to the ATM 250. They are NOT equivalent at all.