I have the Studio and although I only have Accuquilt, Accucut and DayCo dies I still like the option of adding Sizzix to the mix if I choose. Accuquilt does list Studio dies on sale about 5 times to 1 over Go dies but then Studio dies are more expensive than Go dies. I've always felt Accuquilt was the front runner in the die cutting market however just this week though Sizzix partnered with Missouri Start Quilt Co. and there's a kick-starter fund for a Sizzix/Ebony Love partnership. I don't know if you are familiar with Ebony Love but she's a die cutting guru. Check out her videos on YouTube. And download her EDeN chart which will help you cross reference dies.
Having been a customer of Accuquilt for awhile I can tell you there website is often extremely slow sometimes and once an order is placed that's it. There's no changing anything. If you make a mistake (such as adding the same die twice) you own it. Ask me how I know.
There's also a great group on FB called Accuquilt and beyond. If you're not a member you may want to join it.