Needs more buttons. Whether you're a gamer who uses his mouse all day to frag people, or just someone with custom button settings in their IDE/graphics program/browser, you need more buttons than that. Why not embed one in that massive thumb groove, for a start?

Before thinking about buying a new mouse, try turning the pointer sensitivity to maximum - it may take a few minutes to get used to, but it cuts down on a lot of hand movements.

Mouse-related RSI means I already switched to using my mice left-handed some years ago and won't be switching back. But this looks like being right-handed-only.

For the same effect you could just get a trakerball.

OK, you've succeeded in terrifying me that my regular mouse is going to knacker my appendages, now where's your evidence that this more expensive one won't?

This is nothing like a toy Stingray. I know, I had one when I was in short trousers (actually no trousers of course).

Marina, aquamarina ...

I'll get my towel.

The biggest aggro to the RSI is the mouseclicking motion, the curl-down of the main fingers to click. Mate of mine noticed the same thing. I don't think this will help as the mousebuttons require substantially the same action.

I use a trackball (happens to be an expensive kensington, but not as expensive as I'd thought looking at these prices! Actually it was cheaper than the cheapest of these meece). Mouseclick is done with thumb, side of hand or heel of hand depending on your mood.

It stays in one place so you don't need much desk space but the downsides are you need a smaller than normal keyboard (drop the numeric pad) to keep it ergonomically close, it's difficult to use at first (takes a couple of weeks) but once you've adapted you'll never want to go back and what no-one tells you, you need to keep the ball and rollers very clean. It's much more sensitive to dirt than a mouse.

-independent user, not linked to kensington.

(oh yes, there's no rip-off handed version. One trackball does sinistra & dextra both fine)

Looked at photos. Looked at my hand position on the symmertrical unergonomic-looking Apple mouse, and it's identical. Wrist is elevated,fingers relaxed. Most movement from the whole forearm.

Turn to PC on the right side of my desk to see what happened. Still relaxed, but wrist grounded.

Try to figure out the difference. Due to desk space, the Mac mouse is rotated 90º. Problem on that side is that there's no support for my left arm while typing.

My conclusion is that what people need isn't a new mouse, it's a new desk. I always preferred a corner desk, and I think this is why.

Or something.

when I found myself with cramped thumb, from using mouse too much, I just switched to pen & tablet. Much better.

I've used the same cheap as chips mouse every day for a few years now: http://www.octigen.com/DB/Products/mouse-opt-big.jpg - simple, jobber that let's my hand get on with it instead of some botched attempt at ergonomics.

Sensitivity is set to max and I've got ample deskspace. I've had no real probs.

Extensive use of a Dell XPS M1330 laptop in the evenings can sometimes induce a twinge.

After a fortnight of using the Samsung NC10 netbook my trackpad finger has ached like hell, even with max sensitvity and momentum etc turned on - there's just nowhere to rest your wrist (though this is an inherent issue with all netbooks).

I posted above re. a kensington mouse. It has a very large ball and you roll it with the flat of your hand. No thumb needed. I repeat, I recommend it.

Dead right about health & safety & ergonomics, but everyone seems to find out the hard way.

My girlfriend had her carpal tunnel release surgery a while ago, and she's been really happy with the results. No more pain, and no more numbness, just a pair of useful hands once again.

Interestingly the consultant she used was of the opinion that there's no such thing as RSI, only carpal tunnel syndrome.

It's important to get a good surgeon though; my girlfriend was back at work in less than a week after her surgery, and was completely pain free after a month.

One of her colleagues had it done by a different surgeon and was off work for three months, and the colleague is still in pain even now. Conversely my girlfriend can't believe how much better her life is now.

I'll also mention that although carpal tunnel is one problem, there can be other things that cause hand problems too. Just because you have pain doesn't always mean it's carpal tunnel syndrome.

Personally, I suggest you get a mouse without a wheel; a rocker switch is far better ergonomically IMO. It's that come hither motion on the wheel that caused me problems.

The best solution I have found for me that deals with the RSI is a graphics tablet, roughly £29 from Argos. It can replace a mouse quite effectively if you get the right one.

I think my RSI is connected with going blind. Enough said!