Hi,
As long as MCLR is disabled I can't see any problems doing that once the circuit is in its normal operating mode.
However, if you're programming the PIC in circuit it might be a problem since MCLR is also the Vpp pin which you now have jumpered to a "normal" pin. I don't know for sure if this would be a problem but I think it might.

The internal protection diode on "the other pin" would clamp the voltage applied to the MCLR-pin by the programmer to just above Vdd which would prevent the PIC from entering programming mode. Using a diode as the "jumper" from RA5 to MCLR would protect RA5 from the high voltage applied to the MCLR-pin during programming. Or, perhaps, use Low Voltage Programming - I've never used it though.

Obviosuly, if you're NOT programming the PIC in circuit then I can't see any obvious issues.

May require some investigation/testing.

/Henrik.