Depends on what you plan to do with a DMR.
Its a half way house between an ordinary assault rifle and a sniper rifle.
If you are going to have it locked to single shot and be the subject of a minimum engagement distance anyway, you could argue that you might as well just go to a full bolt action sniper rifle.
If the role of carrying a DMR in a squad appeals, then you might just as well stick to the normal fps limits and make your rifle a cosmetic DMR.
An increasing number of sites are asking for "real world" DMRs, so you couldn't just put a high power scope on an MP5.
This is slightly contentious, especially amongst skirmish sites.
We only do milsim, so we ask players to enter into the spirit by trying to adopt a rifle type that is used in the real world as a DMR. We have a 420fps limit with MED of 30m and rifles have to be semi only.