I say give them 9. For two real reasons.
1. It allows them to carry two full sets
2. It is nearly impossible for a player under 150 to earn enough FSP (mainly due to the ever increasing market prices) to get more slots unless using real money
So giving them 9 might help new playes stick around.
Using the argument that players started with 3 so therefore so should everyone else is wrong. People could buy FSP's for 10k gold back in the day and now they are 16 times that and lower level players are still only earning the same amount of gold.
Well lets give them some more stamina also and stamina gain and any other upgrade that can help them. I mean it is so hard to get fsp now so we need to give the players more at the start of their game.
What do you have against new players sticking around? I know when i started playing one of my biggest things was BP space, and honestly if you think players can afford them without reall money then you are kidding yourself.
Stam gain and other upgrades you upgrades you mentioned (although sarcastically) is babying new players whereas i feel a few more BP slots would allow them to work on different setups and allow smarter setups because there are numerous options at lower levels especially. Also it would stop people having to us the AH and mailbox as temporary spaces because that is not what they were designed for.
Although I don't know why I'm bothering giving any reasons at all when it seems all I need is a sarcastic remark.

