I know, for example, BB7s are specified as mtb or road specific, to do with the different cable pull.
What would happen if I fitted road callipers to a mountain bike, or mtb callipers to a road bike?

shimano mtb caliper worked on my road levers ok. changed to bb5 road, and other than having to adjust for pad wear slightly more often i really can’t tell the difference.

mtb calipers on a road bike is horrible ….

i had this on my roadrat – it worked to a point but the lever just didnt pull enough cable and invariably i ended up wit the levers almost touching the bars to stop. the pads could not be any closer without rubbing but needed setting to this point often(weekly) or i ended up pulling to the bars with no power.

fitted roadie bb7s from ken_sheilds and it now works wonderfully and ive yet to adjust the pads after 2 months of riding.

So, if you fitted road calipers to MTB levers, you could have much more pad travel and set them further away from the discs for greater crap avoidance and/or avoiding wobbly-disc-induced rub. And you have increased modulation tweakyability (if running SD levers)?

I’ve got MTB BB7’s on a Cotic X. they work. I can stoppy the front.
the best thing i did was to use a solid cable (nokon sp) on the front, much better feel. shame the rear has got full length outers.

I put a rear road caliper BB5 on the MTB it had no stopping power at all.

If you had some old MTB canti levers, they’d work with road caliers.