As others have said, mx red is purely linear and light. Its activation is about midway through a complete downward stroke at a force of about 45 cN, but you cannot detect the actuation by sound or feel.
Topre switches are tactile with a feel somewhat like that of tripping a weighted piano key on a real piano. Actuation force is palpable and occurs at about 45 or 55 cN, depending on the switch.
I have briefly tried mx reds, and I have extensively used the following:
RF 87u 55g, RF 87u 45g, Leopold FC660C 45g, HHKB Pro 2 45g, Novatouch 45g.
Although these Topre-switch boards have the nominal switch weights as indicated above, and the 55g feels a bit heavier than any of the 45g, the 45g boards feel somewhat different from each other. The RF and Leopold boards feel the most solid to me. The HHKB feels the least solid, probably because of its case-mounted switches as opposed to steel plate-mounted switches. The subjective switch weights also progress for heaviest to lightest as shown in the order above. At first, the RF 87u 55g felt a bit too heavy, but now it is my daily driver at home; I prefer it over all the others owing to the overall solidity and sound and feel of quality of the board. The RF 87u 45g is a very close second. The FC660C has excellent sound and feel, but I prefer either a TKL or 60% layout rather than something in between. At work, I use the HHKB Pro 2 -- I love the 60% form factor and layout. The Novatouch is a good board, but it feels a bit too light for me.
When I am not using my RF 87u 55g or HHKB Pro 2, I like using an IBM XT or IBM SSK.
Based on my switch preferences and my brief testing of mx reds, I think reds would be too light for me and that I would be more prone to errors arising from accidental key presses from the lightness and lack of tactile feedback.