In reply to Voltemands: I have the Garmin 500, albeit bike specific, got it for less than £200 brand new with cadence/speed sensor and hr monitor. Linked to garmin connect is pretty good. Also links to ant+ power meters (not that I can afford one, with the garmin look pedal one at over a £1000!).
If you go for the 610 and get the gsc10 speed cadence sensor look on eBay for merekbikes and there is a stem mount (carbon) that would put the watch in front of the stem if you don't want to wear it or so you could see it clearly for cadence and speed. The sensor is £40 and stem mount £23.