Have fitted a large-ish number of the Casio's over the years and remember when the first units came out, amongst claims of 20,000hr lifetime. We've only had two go down with major pixel failures, but they were replaced under warranty without any trouble. No different than other brands in terms of early life failure, but clearly superior on lamp performance criteria.
The Casio do run hot, particularly the skinny "XJA" type, which look gorgeous, but can be a bit noisy if it's hanging near to your head. There is also an "M" series which is a bit cheaper and housed in a slightly bigger chassis which runs a bit cooler. Originally, the M series had inferior optics which meant that it didn't have the zoom range of the A series. The A type would drop onto most ceiling poles and just zoom to fit - whereas the M usually needed a pole move. I think the M and the A now have the same zoom range - so all good.
I would obviously recommend them if you can afford the extra cost.
As for the BenQ, I wouldn't let the ramblings of a sales person influence you either way. The old "watches and calculators" argument is years out of date. BenQ may well deliver a quality product too, but they haven't been out as long and been tried and tested in the field as long. Hopefully they will offer a competitor to the Casio and provide some competition on price.
