until identity I played with one loadout per raider (didn't spend money). It's fine, yes, not every raider was usable everywhere and I never equipped killerball on Schneider because yama was mostly useful.
However I played this game for quite some time and with identity I invested 10k M-Coin.
In short, the inconvenience is acceptable and like the game, and play quite a bit, I recommend you buy M-Coin, and compared to skins, the loadout-slots are quite cheap. Some skins (especiall naked Loath) are still too expensive and I'm waiting for the 40% cut.