How will using "vdwtype = Cut-off" instead of "vdwtype = pme" affect the results?

GROMACS version: 2020.3

I am running Gromacs on a GPU machine, and in order to make it work, I needed to change the value of the parameter “vdwtype” from “pme” to “Cut-off”.
How will this affect the results? Is there any tests I can do to check if this introduces a considerable error?

A brief description of my system:
It consists of the zeolite H-ZSM-5 with methanol molecules in the micropores. The force field for the zeolite is the following:
For the time being, I use the traPPE force field for the methanol molecules.
The goal is to compute the self-diffusivity of methanol in the zeolite.

You should use whatever method with which the force field was parametrized and validated. You would need reliable target data (e.g. reproducing some known quantity) to see if changes to the nonbonded scheme introduce error.