Orings reduce the total travel, probably by about 6-8mm judging by their thickness though I've not measured it. Traditional Cherries would register at about 25mm and bottom out at about 40mm. So the user would have to train to depress to at least 30 but no more than 35 mm depth. That takes practice, and practice requires making mistakes. The orings bring the bottom of the stroke up into the range where the user needs to practice releasing the key on his own. If you're bottoming out on a mechanical keyboard, you are negating the real benefit of the device.

I've not used the low-profile switches, but I believe that they activate at around 12mm and also bottom out at a lesser depth though I don't know where.

This is why I highly recommend browns (any manufacturer) for new mechanical keyboard users. It is much easier to train on the tactile browns. You could do it with blues as well, but blues are just too noisy for office work, and gamers say that they have too long a reset stroke to be good for gaming. Once the user gets used to not bottoming out on browns, moving to a Cherry red keyboard is absolutely amazing. Typing on reds feels like floating on a cloud, it becomes an enjoyable experience in its own right, once you learn to effortlessly not bottom out.