Thank you for your responses everyone. Though I've not received your PM nanofrog yet.
My initial plan with shelves was to go with nice oak shelving (as this is a study rather than a lab) but the price for that was even more than the stainless steel option!
The annoyance factor of feet going through the mesh and it being hard to hide wires are good points - I'd thought of having a power-strip such as are used in computer racks and wondered if the wiring could be put through the uprights of the shelves without giving rise to a rust spot and a weak point or perhaps normal conduit wouldn't be too intrusive.
I wouldn't keep small parts on them without using Really Useful boxes (I have most of my junk in such boxes). The shelves would be used either for instruments or for stuff in boxes. I have a lot of book shelves elsewhere in the house so I probably wouldn't need to keep books on them.
It is hard to make electronics anything other than slightly ugly unless you confine yourself to vintage wood and brass instruments!
The plus points of wire shelves in my mind was that they are minimalist and look quite good in the photos I've seen of other's labs. They can be earthed to avoid static (though should they be earthed via a 1Mohm resistor or directly?) and they are strong. Also the holes does allow air flow for cooling which will be good for things like power supplies.
I did look at the steel and fibreboard racking type shelves which are very strong but the room is small and I think they would dominate and be a little too industrial (I'm sounding like tv-makeover interior designer
). The other thing was the waiting time on the ones I liked is something like 45 days!