Just my 2 satoshis, but Coinbase has been a nightmare customer support-wise. If you're still able to buy, hopefully it won't affect you.
In the meantime, I switched to Gemini and love them so far. Only supports ACH or wire transfers (no credit cards like Coinbase), and while you can deposit and buy BTC or ETH immediately, you won't be able to transfer your coin to other exchanges for trading alts until you deposit to Gemini clears. Gemini also seems to be the easiest to deal with when withdrawing back to your bank account from all I've read.
That's all just for buying BTC with USD/fiat, of course. I don't believe Luc really buys in at all that way, and most of his trading seems to be on Bittrex and HitBTC. He can certainly answer that better than I, of course. :)
I've noticed that not all wallet formats accept mac (yet, anyway). Does gemini support mac?
Honestly not sure on that... the only wallet I've messed with was a transfer from Gemini to MyEtherWallet which - as far as I know - doesn't have anything to do with Mac vs PC. The rest of my deposits so far have gone to exchanges for trading. Sorry I can't be more help!
I appreciate the reply either way... Thanks!
Just my 2 satoshis, ha, nice.