In reply to Derry:
I used one down in Pembroke (hired) last summer and they seem pretty robust.
The hire shop seemed happy they would last a good while.
Given the hire cost I think they expect them to last a good while.
They would have to be hired out for about 30-35 days to break even, so I'm thinking they'd be expecting 50-60 days minimum, without incident.
Hire kit gets much more hammer than owned kit IMHO.