Escalation is a superior way to practice mechanics compared to DM. Just this fact is enough reason to never remove it, like the current update wrongly did. Here's why it's better:

1. You actually take duels instead of getting killed from the back.
2. You take 1v2, 1v3 and 1v4's like in real game.
3. It's more fun.
4. Some weapons can't be practiced in DM properly, but can in Escalation, e.g. shotguns.

The only downside is that you spend disproportionate amount of time with weapons that are hardest to kill with like Shorty and Marshal.