I like Fidelity better than Vanguard in regards to web interface and customer service. Vanguard has better funds for the way I wish to invest. Since I plan to invest in a dollar/cost averaging manner 1-2x/mo, it will be smaller amounts and so buying Vanguard ETFs through Fidelity would really eat into my money (given a moderately diversified portfolio of around 7 ETFs). Given all this, I have looked into transferring shares, and see no fees mentioned to do so. Doing a quick google search has lead me to believe that it will cost nothing - http://www.onlinebrokerrev.com/commissions_and_fees/account-transfer-fees.php
This being the case, is there any downside to using the free transfer of shares, to avoid the brokerage fees?