Hi Lord Spandex Masher,
You should NOT use wet performance unless the runway is wet. Damp is not wet.
Please see Page 64 (Appendix F) or read the whole document.
https://www.iata.org/iata/RERR-toolk..._Reporting.pdf
If the first third of the runway was damp, but the last two thirds were dry - then I'd agree.
If the tyres were newish, the runway was grooved or the surface drainage (surface shape, slopes) & the tire/ground interface drainage (macrotexture) & the penetration drainage (microtexture) was good (see page 16) - then I'd agree.
Otherwise, if I I thought the braking action was less than dry - then I'd use wet figures.