I hit DM the year before the AmEx waiver went way up for DM, making DM likely unreachable for me going forward.
It all depends on what you value out of DM over PM.
My opinion: PM is really good; DM is better. Just how much better is in the eye of the beholder.

Way better domestic UG percentages, which have been dropping for me as a PM, driving me to either accept C+/Y or buy-up to F in many cases.
3 choice benefits versus 1, including additional choice benefits not available to PMs.
You do get through slightly faster as a DM than a PM but I think I've only waited more than about 5-7 minutes once or twice as PM in the past few years. I also noticed slightly more favors & waivers as a DM but again, still get treated pretty well as a PM and can't say if the drop is completely from me going from DM to PM or if it's also a combo of Delta changing it's models slightly as well.
I did claim GUCs and was able to use them though not on an amazing route (used them on BOS-AMS/AMS-BOS). AMS-PDX was also available but I was meeting a companion for whom PDX wasn't a routing option. Like with miles though, the key is flexibility if you're looking to clear in advance though some routes like LAX-SYD & ATL-JNB will almost always go to the gate.
RUCs are the same, just domestically. Depends on the route. You can get those as a PM.
I've received good IROPS handling as a PM but yes, it was slightly better as a DM. I got the Porsche transfer at LAX which is the only reason I made my connection to BNE when I was a DM.

In short, if I could hit DM, I would. But I can't, so PM is good enough, though it has also offered the opportunity to get some lower tier status with other airlines too.