In reply to Tim Davies:
I have used the iphigenie app for years and it works well for me. I particularly like being able to add in the slope angles layer (which is 'fadeable'). Not sure if that feature works on Viewranger - maybe Tom B can confirm?
As above - about €14 a year (same price as one IGN Top 25 paper map...), pretty sure Viewranger is same price for accessing the IGN data.
Post edited at 17:24