I tried a Bad Elf GPS Pro inside the 320 yesterday and all I can say the reception is absolutely great. It gets strong signals almost everywhere inside the cockpit, all you need is to keep it close to any side window or even in the front windshield. Really great stuff.

Now I am just wondering if there is any decent offline map on the market compatible with the gps position?

Better check the regs first....

I'm using Memory Map. Works well on Android and there is a ithingee version as well. Download the maps (most will cost money) and then install on device for offline use.

Memory Map is an excellent application, but unfortunatelly its worldwide map availability is very limited.
I just found out this new App made by National Geographic, called World Atlas. I think this one is awesome, with really nice graphics and you can dowload several map types (satellite, political, roads, etc) for offline use. Excellent stuff.

Galileo offline maps for iOS and Android work very well! Its cheap and you always have fresh maps although if you download the whole world it'll take up 13-15 gb on your device. It can also track your movements, speed etc

I have a Garmin Glo which works well in light aircraft but not in the 787. I have tried it in-flight against all flight deck windows, the overhead hatch, crew rest and in various locations around the cabin. Nothing!

Works well in an A320 cabin though.

A mate of mine says, allegedly, the Bad Elf works really well in the 767 close to any of the side windows. Unfortunately our company realised that us being able to plot our position accurately on the Jepps was a stupid idea and ruins their plans to embarrass everybody in NRT's taxy zone of confusion, so they've contrived to disable the 'ownership' function. Yeah, let's turn something off and reduce safety :rolleyes: