The 405 still has a bike mode though doesn't it danowat? You just can't easily switch between run and bike mode like you can on the 305 right?
Also @Trip: I think you must be thinking of a different model, the 205 is exactly the same as the 305 in size, shape and functions, it just lacks the heartrate monitor. Perhaps you had the 301 or the 201?
Still I agree though, the 205/305 is not that chunky. It is a fair bit bigger than a wristwatch but not uncomfortably so.
If I had the money I probably would have got the 405 as it really does look the business. If you just want the functionality though and either want to save money or are not bothered about what it looks like then the 205 or 305 is perfect. For me, as money was tight and I didn't want a HRM either, I got a 205 and payed just over half what a 405 would have cost at the time.