more specifically, can a zee 10 speed shifter be used with a 10 speed deore or slx mech on a 10 speed cassette? if I swap, I'll only need the rear shifter, and dont like gear indicator windows, so the zee would be perfect!
As long as you stick to the same general type (road with road, mtb with mtb), you should be fine.
Be careful when mixing road and mtb parts, the pull ratios are different.