Help Choosing Group Within Securitized Products / Mortgage Trading

Wondering if anyone can offer advice for choosing a group to work for FT within mortgage trading (i.e. agency, non-agency, whole loans, CMOs, ARMs, etc.)

I've been thinking about CMO Structuring because you get the opportunity to learn about mortgage derivatives inside out. However, I know that during the first few years I won't be trading, but will be putting together 'deals' .

Does anyone know the typical career path for an analyst starting out in CMO structuring? Do they eventually get to the trading / market-making role or do you get pigeon-holed?