All of the currencies are volatile, that's a given. A 50% decrease in BTC over a few day period proves that. Whether or not a vendor will trust an alt coin can't be based solely off that point, as all of them are subject to it.
With the myriad of other players in the marketplace, this is the only one I've seen with a dedicated target niche, and as I've pointed out, they've targeted a huge player.
The mainstream media barely pays attention to LTC, let alone any of the other versions, however, I can see them paying attention to this one, as Rule 34 states, if it exists, there is porn for it. Now there is an alt coin for porn. Even as a joke, it will draw attention.
The "bonus" system rewards dumb luck, but that kind of payout can entice a huge army of miners to jump on the currency, as it's not only readily mined, but everyone wants to get those winning blocks.
The inclusion of a miner in the wallet, is the first I've personally seen, and reduces the hurdle to installation adoption.
Will this prevent porn companies from adopting other coins? No, there's no reason they would chose to avoid BTC/LTC, but if the implementers do their job right, they could provide the fire which drives adoption, and would therefore be strongly in the running as a competing currency.