The GLI instrument cluster will fit into a CXI no problems and work. Just the power windows and rear disc brakes would be a pain to install etc.

There is virtually no price differences between the CXI and the GLI on the second hand market. If you want all the power mirrors, windows, tacho and rear disc brakes, then just wait for a GLI to pop up.

Although if you find a nice CXI, then really, there is not much difference at all.