Toilet and (2) 45's vs long 90

I have a raised floor where I'm installing a toilet and coming right out of the toilet i can do one of those longer 90 elbows or (2) 45's for a gentler angle coming right out of the toilet mount. The advantage to the 90 piece is that i can get a steeper slope by an inch or so.

Is there really much difference between the 2 ?

Under normal circumstances will the 90 possibly clog in time ?

Either is fine.

WHY do you "need" a steeper slope with the elbow? If you have the "proper" slope it doesn't make any difference which fittings you use.