I much prefer Treks. I find them easier to put on, even with pastern wraps. I have never lost one, and rarely had twist issues. I ride brushy, weedy trails in all conditions and the only Velcro issue I’ve had is the overstrap opening up when I let my skinflint nature keep me from putting new ones on (every boot comes with a spare). Cavallo does make buckle straps for the Treks.
I find Scoot boots less forgiving in fit over the trim cycle. I’ve had twist issues, rubs, pressure scurf from mud straps tightening as they stopped the boots twisting, and the endurance gaiters tend to shift. Some people have trouble putting the endurance gaiters on, but as they’re identical to the Boa gaiters I had for my Boa boots I have no issue there.
I have used both for turnout (full outdoor board) and the Scoots were the ones that rubbed holes through his hide after three days. I was able to wrap the rubs, put Treks over the bandages and do a 15 mile training endurance ride without making them worse, or making him sore. I have used them for turnout for a day or two without rubs since then. Scoots are better in hot weather as they hold less heat in the foot.
When I use Treks for turnout I swap his pastern wraps out for a dry pair daily. Treks are great for putting over poultice diapers. No duct tape required, just poultice, diaper, vetrap, Trek.
It gets very cold here and I find the Scoots harder to put on in the cold. I dislike having to use a tool to get my hoof boots on (hoofpick to hook front straps). We can get weeks of frozen mud before getting a decent snow cushion over it, so I am using boots in freezing conditions.
I also find my horse stubs his toes more in the Scoot boots than he does in the Treks. I haven’t tried trimming the boots to bring the breakover point back.
It really does come down to which boots fit your horse. I rode a friend’s horse this summer that had Easyboot Epics and Gloves. They were great for her horse, apart from the tools-required application and, for the Epics, removal. I’d tried Easyboots previously and found them useless for a horse that didn’t have the ideal proportions and angles. Both of my horses have done well in Treks (one even did 25 mile Endurance competition rides).