I'm seeing some difficulty in training, specifically in lower levels due to the low mob spawn. I don't know if the map is regulated by how much the population is within each channel or whatnot, but they should spawn at a more numerous amount only because currently it is too little compared to what a normal GMS server back in .62 would be like.
Are there certain maps that you have in mind? Most of the maps that I can think of already have an insane amount of monsters spawning :O
The more popular locations are filled to the brim with spawn: Wild Boars Terrace Hall Forest of Golem Wraiths Ghost Ship 2 Wolf Spider
Copper Drake spawns are low. Pig beach spawns are low. Truckers is kind of low. Chief Grey and it's dna drop are near non existant. Ribbon pigs are very low.
^ To add onto that list, One of my favorite "mid" level areas has what seems to be a much lower spawn than it had in GMS and that would be Lower Ascent. At this point though, I'm guessing that we'd be better off logging onto the Open Beta server to check out the maps and leaving this kind of feedback in that section of the forums
I think it is good to have alternatives, not just for training but also for questing. For a quester like me, some quests are just tedious to do cause of low spawn/or decent spawn, but terrible map like CloudFox, Extra A/B/C, Stone Golem etc.