LX Nav make some nice instruments but I strongly dislike the fact that their standalone varios like the S8 or S80 cannot be connected to LX80xx or LX90xx navigation displays.
This essentially forces one to toss out your expensive S3/S8/S80 standalone vario if you want to add a nav display later on. Not cool!

LX Navigation take the compatibility route with their EOS vario.
You can purchase the EOS vario which can operate in standalone mode and then add a LX Zeus navigation display later on when you have the cash.
Not all of us have $4000 to $5000 to upgrade the entire instrument panel in one go, so this approach makes more sense to penny pinchers like myself.