I have two sets of boots, both a high-top cut (the Alpinestars S-MX 2 boots):

And a pair of Dianese full boots (TRQ-Race Out boots)



To suggest that the high-tops have the same protection of a full boot is stretching it a bit i.e. they may have the same slide characteristics due to the addition of skid/slide plates at the toe and heel areas, but high-tops don't stop the ankles from moving in an underpronating or pronating-type movement (i.e. think about walking and going over on your ankle...can't do that in full boots). Also, high-tops don't tend to have the armour/lateral stiffness needed to protect the achilles tendon should a crash occur. And of course, taking debris to the shins at over 100km/h is a wee bit on the painful side.

Again, I do wear both under differing circumstances (e.g. sometimes when I go to work, I'll wear the high-tops given that it's just a 6min ride and I can wear those shoes all day), just figured I'd add my voice to the discussion (in the end, take the time to understand there's supporters for both types of boots - review the facts and make a decision based on what you feel best serves your needs).