Garmin Lakevu HD demo maps

[dsm1212]

I'm going to pick up a 7" MFD this spring to replace an older GPS so I can add a transducer too. I'm limited in space where the current one is on the console. I can fit in any of these: garmin 7607, simrad nss7, or raymarine e78.

The nss7 evo3 version has about 2x the resolution so I'm inclined to go that way if it becomes available in the next month. But I like the garmin 6" transom mount transducers (52). The locked down maps on the garmin really bother me though. I love the navionics maps and I'm already familiar with them from my nexus.

I stopped in west marine and pulled up winni on the 7607 unit they had on display using the LakeVu HD maps. I checked 3 spots and 2 of the 3 were clearly wrong. Could this just be the demo maps? For example, at the sandbar near west alton marina across from sleepers the demo map showed 46' deep on the sandbar to the east of the black markers. I know that is like 3 feet. I pulled it up on the simrad evo2 and it was correct at 3 feet. My main question here is whether the demo maps are just borked or are the garmin maps this bad? Maybe someone could check that spot if you have current maps?

The sales guy insisted that the next gen of garmin units was back to supporting 3rd party maps including Navionics but I can find no information on that anywhere. Does anyone know anything about this?

I'm leaning toward the simrad because of maps, resolution, and having knobs. My boat is a 30' searay bowrider with twin IO mag 350's, not much of a fishing boat, but I'm getting mixed messages on using a transom mount transducer and the lowrance totalscan transducer is like 10" long too so that worries me in the middle. I'd like to have downscan to see the bottom of the lake. Any comments on transom mount?

thanks

steve