I currently run about 40 mpw in NB 880s and Asics Gel Pursue. Both are heavy but still feel about the same after 300-320 miles. My issue with them is I feel like I always have to concentrate/try to force midfoot striking with them (when I got them ~6 months ago I was trying to change from heel to midfoot.)
Recently I tried on a pair of my friend's On running shoes with a 6mm heel-toe drop and 2.5 oz lighter than my current shoes, the NB having a 10mm heel-toe drop and the Asics having either a 8.7mm or 10mm (still feel like it promotes heel though). The On shoes felt great and really light as well as direct and responsive, and it was much more agreeable to run midfoot. I don't know how much difference a few mm makes when it comes to heel-toe drop, but then again any running shoe obviously feels different than running barefoot, which is automatically a midfoot stride.
My question is, if anyone here has trained in On shoes, how durable are they? Additionally, if I wanted to try training in flats like Nike LT 4s (inspired to ask by a recent thread here, not a big fan of cushioning anymore and want to try some low-drop more minimal stuff), should I try to ease them into my training because the lower drop might put some strain on my calves (same thing with low drop shoes/lightweight like On)?