The Alpinestar S-MX 4 Waterproof Boot is a great boot with a lot of support on the ankles. I have already tested the support in my recent low side during a track day. As my boot was clearly hit by the bike when the low side occurred it did protect my foot and ankles (Sorry I wont test this again without a boot to see if it was actually protected my foot or not). I do have to say I have worn Alpinestars while racing Supermoto and during normal road rides for years I have had nothing but good things to say.
These particular boots are comfortable and a nice design as well. I did encounter after only two months the Velcro on the zipper broke on the right boot but was easily fixed at the local tailor. Besides the Velcro breaking I would recommend these boots for any rider serious about track days or riding on the streets both. I also have tested these boots in heavy rain and my feet were still dry after my ride. Let us know if you have a pair and what you think of your boots and the wear and tear.