Do you mean that there’s some kind of numbness/pain/tingling in the tips of your fingers? If so, you may want to consider other changes to your posture or typing style.
Tingling is the correct word, yes.
Hm. Be careful out there. RSI is not something to take lightly.
The first thing I’d recommend is try to have a good posture while typing. If you can, keep your neck straight with your display straight in front of your head and your desk / keyboard tray low enough so that your elbows can stay at a 90° angle, with wrists floating in the air rather than resting on a table. Some experts recommend switching positions from time to time, or taking breaks to stretch or walk around. Several of my friends have found using a standing desk (either part of the time, or excessively) to make a big improvement. Just generally making sure to get enough exercise outside of work can also make a big difference.
With respect to the keyboard itself, try to keep your wrists in as straight and neutral a position as possible, and try to not use too much force when typing. If the Model M is tiring, certainly feel free to use something else. Personally I find that buckling spring switch or something similar (I particularly like Model F, clicky Alps, and clicky “monterey blue” SMK switches) helps me to avoid putting too much force into the bottom of the keystroke. But it’s certainly possible to type pain-free on all sorts of mechanical switches, even on a standard keyboard layout.
It’s possible that getting an “ergonomic” keyboard would be more comfortable, though this can be costly. Some of these have shapes that are radically different from the standard keyboard, such as the Kinesis Advantage, Truly Ergonomic, or Ergodox, but note that these usually take a week or two of training to get back to full speed. Others just have a split in the middle or some tenting or both, for instance the Cherry G80-5000, IBM M15 (both excellent but out of production and quite expensive used), or Matias’s upcoming Ergo Pro keyboard.
Even on a standard keyboard, other character layouts such as Dvorak or Colemak can reduce the amount of uncomfortable finger motion needed (though these also require substantial training).
