Should I make a Gdax account?

Hello,

I recently made an account with Coinbase and subsequently my first purchase of Bitcoin.

Currently, my limit is set to $100/week. I understand that as I spend more time with Coinbase as a customer, the limit will increase. Unfortunately, there doesn't seem to be any information anywhere indicating exactly when or by how much one's limits will be raised (there are numerous topics on the website's very own message board, and they don't, in my opinion, adequately address the issue).

Throughout my research, I read mention of GDAX (which is a partner or subsidiary of Coinbase?). It seems to be a pretty popular/simple method for buying/selling Bitcoin, but I thought the same thing about Coinbase (and my experience thus far, albeit not very long, has not been the greatest).

I am interested in Bitcoin mostly from an investment standpoint, and would like to make more substantial purchases than $100 a week.

Would creating an account with GDAX be a good option for me? I'm quite new to the Bitcoin world, and I'd rather not stretch myself out too thin with different accounts, wallets, etc... but I don't have any idea what to expect from Coinbase, in regards to the purchasing limitations.

Thank you for reading and thank you for any helpful advice,

-Faj