Best learning tools and simulators for Garmin GTN

I’d like to refine my use of the GTN650 by being able to practice/rehearse use during an approach sequence. I am confident with the basics, but want to avoid surprises with some of its more powerful sequencing features. I use Apple computers/tablets rather than PC/Windows.

There’s quite a lot of learning material out there:

• Garmin’s new eLearning training course launched last month (£76 for 180 day subscription)
• Garmin’s GTN trainer for iPad App. (Free for 30 days, thereafter £19)
• Pilotworkshop’s “Pilot Friendly” manuals (£30 each)
• A PC based simulator that came with the product (doesn’t work on my very old laptop)
• A “plug-in” emulator that works with Microsoft FSX Flight Simulator (and/or the commercial P3D variant). I don’t believe there’s anything that works with X-Plane yet.

Any views on what’s worthwhile? Do you need a full flight simulator setup or are these simpler Apps adequate?