It does perfectly fine in light weight potting soil if kept rootbound and allowed to dry out between waterings. I live in Florida and many fine rooted epiphytes are grown directly in the ground in our light well drained soils. These include bromeliads, epiphyllums, and hoyas amongst others. I had a potted staghorn but wanting to reduce my number of potted plants I planted it outside in the ground at the base of a tree. It has since doubled in size in a season.

Wonder where it got the French bit in the name if it is Platycerium veitchii which comes from the drier parts of Tropical Queensland, Australia.

Where it grows in nature has a drier, sunny winter and that might be the reason for the enlarged foliage if you are growing indoors during winter.

Sorry, have never tried stag horn ferns.

If you check you'll find Platycerium lemoinei is a ficticious name, it's not even listed as an obsolete name for any Platycerium species. It's not unusual for nurseries to invent names to give their product some exclusivity. This is possibly the case here. Your plant does look like P. bifurcatum but is possibly an over watered and over-well-looked-after P. veitchii.

I'd be inclined to treat it as a bifurcatum, that's likely how it's been treated so far and is doing well. The thing to keep in mind is that epiphytes live off rain water, some town water is loaded up with chemicals. Over watering can cause problems, even though they're mostly a rainforest plant in nature they do get a fairly dry winter.

It's a very nice plant and with the right name you can also search out the best advice on it. There's a couple of dozen different species of Platycerium, I've only grown P. superbum and P. bifurcatum but would like to get a P. veitchii.