But why should any choice be involved? What's wrong with practicing two different patterns? I've been playing for 40 years, and I can assure you that I've used both fingerings many times over the years. At the very least, practicing a different pattern may help cut you free of the idea that a scale must always start with your 2 finger (which IME is something that folks can get hung up on if they only practice a pattern one way).
My point was that it's impractical in comparison given that much information. Of course one should practice scales in many positions to get the most out of them, Scale A isn't one I'd use. I would rather start at V position to play the tonic and then shift up to VII to continue the scale (now in my stock Dorian mode pattern).
One advantage of practicing pattern A is that it allows you to go into an A scale from V position rather than having to start in IV. If you're already in V when you are called on to play a scalar passage, this is an advantage.
Of course but position V to IV is just a quick shift away, too. In this case I would consider where I am coming from and where I am going, whether it's feasible to make a shift down to IV and if so, how long I will be staying there, what my next shift will be.
I am not a big fan of applying Simandl lock-stock-and-barrel to the EBG, because it seems unnecessary to me. There's no particular reason why a technique devised for one instrument has to be applied to a different one. I admit I do often use 1-2-4 in low positions, but virtually never in higher ones, and I never, in any position, feel the need to reinforce the little finger with the ring finger. It just seems needlessly restrictive. But then, I come from classical guitar (many moons ago).
Well the consensus with electric guys using Simandl is that past the 5th or 7th fret (roughly), it can go out the window. I do not like using OFPT in the lower registers because it feels uncomfortable to me and it's rarely necessary but I will if I have to.
In any position I think you need to be considering the span of your hands vs. the spacing of the frets. My idea of a practical fingering can differ from someone else's in that I will sacrifice the "proper" textbook fingering for something less practical, but more comfortable.

