I've recently found the holy grail of IOS based GPS apps , called "GPS tracks". The guy who wrote it had me in mind clearly.
Quick youtube screen capture of me messing around with it (excuse the clunkyness of the video, my ipad struggles when doing a screen recording and isn't terribly fast model).
It does require an annual subscription in order to download segments ... I think 300mb per segment, but unlimited amount of segments. Importantly, there are custom URL's to add in to attain the Google Hybrid, and Google Street map soruces for download. There are then numerous other data sources available for download offline also. The apple hybrid can't be downloaded "offline" but as with most apps, it caches it anyway so if you do a fly around before a trip, it retains it.
I've found the UI, the tools, the import and export functionality with my KML and/or GPX files is awesome. It's high res, and extremely granular control over most parts of the UI. Waypoints and track lines are nice and fine.
Primarily I download huge areas of data in "google hybrid" (which is satellite view + road/terrain data), Google Street (very good), and then "terrain".
There's also the ThunderForest Maps, and OpenCycle (terrain) which have great bush terrain data in Aus.