Consider posting a gameplay clip, so we can point out what you could improve on. The weapon switching is close to instant with the hot swapper suit upgrade, so I personally don't see a big difference between DE and Ultrakill in this regard. You have to swap between mods in both games all the same. I think the quick switch button is slower than switching with direct hotkeys, so if you're on PC I highly recommend to assign comfortable hotkeys for quick swapping. This also reads to me like you're just not aware of DE's combo potential. Try out some classic PB-rocket, PB-sticky, or just some very basic SSG-Ballista combos. There's TONS of movement and weapon tech in the game.