In any situation where I really need flash (speedlite), the 24-105 F4 can't focus fast enough to be useful. I still have my 28-70 F2.8 because of this. I would use the 35 F1.4 instead.
When under studio flash, I usually use primes, but if pressed I do use the 28-70 F2.8 too. I have never used the 24-105 in the studio, nor do I consider it a studio lens.