Think about it this way.
An ion cost maximum £200 new...and requires Ups to make it feel better and perform better (maybe)...
A DM4 cost the best part of £1000 new...and dont need any ups to make it feel more quality...or shoot better...only ups will improve looks potentially...rate of fire (if needed) and efficiency (if needed)
Solid, sexy damn hard gun...not like the Ion.
Ion is cheap, but good