I recently ran across a problem with pre-wet which has not been reported previously. I was measuring some characteristic curves for Agfa APX 100 developed in POTA. I found that both 5-minute and 1- minute pre-wets basically destroyed the negatives. The density was increased markedly in the higher density region, so that the overall contrast was substantially increased. The characteristic curves with and without pre-wet are shown in www.vsta.com/~alrob/prewet.html.(posted 8578 days ago)However, when I developed the same film in HC-110, there was absolutely no change in the characteristic curve with the prewet. I did some asking around, and I think that for most film/developer combinations, the pre-wet makes little or no change in the characteristic curve, and it probably does improve temperature control and even-ness of agitation.
I would suggest caution, however, when phenidone developers like POTA are used. Technidol is a prime example. Xtol has (apparently) a small amount of phenidone and should be checked. Jobo does not recommend a pre-wet with Xtol, and perhaps this is the reason.