Rgphoto, I'm a newbie to the microstock (Started in January this year) and first of all, from my point of view if you pay 1500 € for each session it will be very very hard to get it back, why? Altought it could be stellar shots you would had to compete against great names in the Micro world (Many located in the forum) plus a lot of clients like to deal with specified photographers due to their unique style. So in general view and unless you have a unique style that pop's from the rest or you have a huge library then you will have a hard time getting some revenue out of a single session. I have a few models not top models unfortunately but they are rather cheap, some are friends others I give them a free portfolio in exchange of a session (That really cuts out the cost) ,having to paid a hairdresser that can do all sorts of things besides hair, like manicure or make up it also cuts the costs. But about the viability of the white background I can't really help you that much but from the point of view of the more experienced I think they are right outdoors have been selling a lot more.
Just my 20 cents. Hope it helps.
Just my 20 cents. Hope it helps.

(This is one of the rare moments I start thinking why I didn't took programing classes
)
) Getty buys Stocksy > Stop > Repeat"