I’ve been seeing a lot arguments recently for using a good quality prosumer type digital camera, and not a dSLR.
The problem with DSLRs is that the sensor is exposed to the elements every time you change the lens, and this can have a detrimental effect, or two.
A high quality prosumer which incorporates manual focus and a decent quality zoom lens built in should be a more ideal solution because it is fully enclosed. Sadly, I don’t know of one which entirely fits this description – the closest is probably the Fuji S9500 – which uses a fly-by-wire focussing ring around the lens!
Such a camera would also need a decent quality sensor, macro function, teleconverter and wide angle lenses too, to increase it’s flexibility. Although, of course, there’s no reason why you couldn’t have different cameras optimised for a particular role. They could be much smaller.