I wouldn't waste my $$$ on a subscription hoping for updated lake maps for Temagami.... What I'd do is power up the graph, check the maps you've got now and compare them to the Navionics maps online. I'd be willing to bet they're identical.
As long as it's not a Polaris 550 fan you're fine. The 500 fans are the ones you want. Top end rebuilds on those are cake, even if you do blow them up.
My opinion..
Too expensive, need a specific charger, no warning of the battery going dead, it just dies. Not there yet, but I'm sure some day they will be.
I've sent them a few of my Calais, they always come back with all kinds of new hardware on the inside and I'm never charged more then the original service amount. Those boys do good work. Which reminds me, I gotta pack some reels up and get them out there!
I've seen both muskie and pike do this out on Gbay. It's definitely odd and I've never caught a single one of them (And you can bet I casted at them lol)
If you're all within the same cell you might be able to move it around. Camper might be tough if you're in Alaska, but I'm sure that feature is coming.