I've used Delta 100 quite a lot with with #25 and #23 filters, and I have found the results to be perfectly normal. I don't think Delta 100 has abnormal red sensitivity. TMX is another story. Because TMX does have heightened red sensitivity, it responds very strongly to a #25 filter. I find that I have to add about an additional stop (4 stops instead of 3) in exposure, and that shadow areas can be very tricky since it is difficult to determine how much they will darken.(posted 8369 days ago)Keep in mind that when you use a filter to darken the blue sky, it also darkens the shadows. Shadows are most typically lighted by blue light--light reflected from the blue sky, not direct sunlight--and this is more pronounced early and late in the day. Therefore, the filter that darkens the sky, also darkens the blue light of the shadow areas. This, in effect, adds contrast and means you will have to adjust your exposure for your critical shadow detail.
In terms of processing for a pull, as someone else said, I've found far more pleasing results diluting my developer opposed to pulling the time. Try diluting by 1/2, but be sure you use enough volume. If you typically develop one roll with just enough developer to cover the film, use twice the volume of the diluted developer. Otherwise, the developer may exhaust itself totally before reaching proper density. As for developing times with a 100% diluted developer, I'd suggest developing 50% longer as a starting point.