The red triangle on the GPS fix in MM works off the iphone's internal compass, it won't be of any use near large lumps of metal. The velocity vector is much more useful.
The power saving options on modern phones aren't as flexible as my old WM phone with its transflective screen. I think the best way to use mapping software on the iphone or Androids is with the screen permanently on, at a high brightness setting & plugged into an external power source, which is how most people use the Aware.
MM have spent most of their development budget tweaking the software to run on out-sourced proprietary hardware. They see themselves as competitors to Garmin & the like as providers of moving maps to hikers & bikers; they don't see themselves as providers of an aviation service in the way that Airspace, SkyDemon or Pocket FMS do. I wouldn't spend hundreds on MM, but they are good value as cheap moving map software.
I did. You need to spend about £75 for the PC & mobile software, assuming you dodge the VAT, and then you still face the hassle & expense of scanning the paper chart & cutting it into tiles at various zoom levels. It reminds me of your comments about DIY maintenance on permit aircraft, ie factor in the hassle of finding a suitable place to do the work, work out how much your time is worth & in the end you're probably better off paying someone else to do it for you.
I see that Ozi have an Android alpha version out. If I was going to do the self scan option, I'd do it with freeware, eg
Orux