I use
http://lastrite.co.nz/products/20-heavy-duty-yardmate-boot for last 12 months. These
http://lastrite.co.nz/products/23-workman-safety-boot for last 4 years at work in construction.
I swore of PU boots due to hydrolisis issues after losing a sole off my Haix nebraskas during a steep descent down a watershed.