I don’t think there are really any major downsides to uniform profile keycaps, it’s ultimately mostly preference. The only thing that might cause issues could be the homing j and f keys if you only get a set that supports QWERTY. But that’s a much smaller problem than not being able to rearrange the caps at all due to a sculpted profile. Blanks are a good option, and forces you to learn your new layout without looking at the keyboard, but I understand the appeal of having that available to speed up the learning process and commit it to muscle memory.