Well according the the A320/21 MMEL no performance calculation required with BOTH thrust reverser inop in the case of Takeoff on Dry and Landing on Dry and Wet. It also says that you MUST calculate performance using the thrust reverser inop table for Takeoff on WET and CONTAMINATED and Landing on CONTAMINATED runways.
My performance manual issued by the company does NOT include a table for thrust reverser inop, so therefore I can't dispatch on a wet or contaminated runway with both thrust reverser inop or land on a contaminated runway.