Im going to watch this topic, because I don't really know.
I have my feet turned out alot, kind of like duck feet haha, im trying to train them to go FORWARD. It is just a habit my feet naturally go into when my heel's go down.
Let me see if I can find photos, haha they look pretty wonky.
(my heels go down really low though, so that might trigger them going outwards..)
Hmmm...my toes are generally straight forward unless I am giving a cue if I am in the arena. On trails they are a little more out, but nowhere close to 45 degrees. Nobody ever told me one or the other...so I will be watching this to see the real answer.
Toes forward for dressage. Im not sure about jumping, but toes forward all the time for dressage, then you can use your calf for aids (so they are invisible) and if that doesnt work then you can use your heel.
From ballet, I have a fairly good turnout with my hips so generally my toes sit a touch less than 45degrees and my horse responds to my cues. However I'm not necessarily doing it correctly.