YES!
I use a combination of stuff Simon. both Android and IOS. Originally i used to use Ordnance Survey "Memory Map" with a Windows App and a PDA. Eventually our wonderful OS decided to update the software and low and behold the new software version would not read the old map file extensions (Bloody clever move OS). Anyhow in there infinite wisdom they offered a bolt on to the software that would read the old extensions for a mere £90 as i remember! Well there was an awful lot of peeved people like me around that had built up a considerable library of (Expensive) OS 1.25 maps. To cut a long story short i found this brilliant App called "Alpine Quest" (QUE Android device) this will read many Map formats and will allow you to create or download maps while online and save them to be viewed and used offline. You can import and export maps routes track and all the rest of the things you'd expect. You can get a freebe but for a few shekels you can get a proper version. Don't ask me how the freebe works can only speak for the paid version and its good. Sadly not available on IOS but at least all my maps are not redundant!
Going IOS another App i use is "Pocket Earth" this will allow you to create or download maps while online and save them to be viewed and used offline, I have used this quite extensively abroad, downloading maps from the likes of google saving them, so when i'm out of the country i can get all the map info you can also set it to pull up the Wikipedia info on POI's which is very useful and you can get Topo information (I think that's another couple of shekels extra).
Tracking etc works fine although i haven't gone into importing and exporting routes although clearly you can do that too.
With regard to GPS i always use an external Bluetooth receiver that way your never shafted for Data usage ..... Don't cry if your IOS, contrary to popular belief there are GPS receivers that work with IOS albeit very few!
This is a great one that i use
http://www.gns-gmbh.com/index.php?id=233&L=1 obviously this will run on IOS as well as Android etc etc
I do have a big library of paper and waterproof OS maps and several compass which is always the first in my sac!!!