How do you get on with these babies? 
Had considered getting one of these for use on the Dark Side, and they're heavily discounted on Merlin's website. However, having read the reviews on Roadbike Review . Com I'm not going to bother. They appear to be very unreliable.
Thanks for the Merlin tip.
I don't have money to waste and have also read the reviews-some pro and some really dodgy.
I have a Strada wireless which was fiddly but the sensors on the back wheel work better.
I would love a HRT monitor and cadence -thought I could get one unit to do the whole lot and not pay £370+ for the Garmin 705 and £80 for Garmin maps etc.
Might see what the options for the cadence unit only and a Polar HRT monitor.
Also when lost I have been using A-GPS on my mobile with google maps and it has been really good in cities but haven't had a chance in the country etc.
http://www.heartratemonitor.co.uk/
Have some cheap prices too.