Citadel GQS

Hello, 

I'm currently in the team matching phase at Citadel GQS having passed the onsite recently (for a quant position). I was wondering if anyone could help me get a sense of what it is like to work there?

What is the typical turnover rate?

How many people make it beyond 3-5 years there?

How's the culture?  

What would you choose between GQS and Securities and why?

I would also appreciate if anyone is willing to answer any of my questions on specific teams there. (private messages)