I am currenly looing at one of two SA Saint AR15's

One with the standard A2 sight -

https://www.amazon.com/photos/shared/iPAhU9MuRcKenTw7CFpCsA.aMJ9BhNT_jP0t3RZwQr4i3


https://www.amazon.com/photos/shared/ySS8dskZTMaw__mfok5psg.-8Apdp7RKKqP_ZvT349Et7



The other with the Pinned Picatinny gas block -

https://www.amazon.com/photos/shared/K6ka5w_bRUiF8aqEJFyyWw.5WlChDpVUTdzNXMWZmeuun


https://www.amazon.com/photos/shared/vjwWbx7aQ0yaCcJUluEfYQ.WJNOmXotrQRHxJ4HsqAN49


Other than the obvious difference between the two, the fact that the pinned on uses "flip up" front sight, and is more greared towards using some kind of optic with a flat top upper where it will not interfer with the sight picture (again through some kind of optic) - WHAT else is there I am missing or the advantage of one over the other before I make a decision please?


Thanks -

Eric

That's pretty much it. One folds and is a back up. One doesn't and was built as a primary, but can still be used in conjunction with a lot of optics.

Any other down side to choosing one over the other?

Thanks -

Eric

For the railed gas block, you have to use metal BUIS if the rifle doesn't come with them or you want to change it. The FSB has a loop to attach a sling (and a bayonet lug), the railed GB looks like you'll need a QD mount on the polymer drop-in handguard.

Are you planning on running some sort of optics on it? If so, what?

Not currently, but if I were it would be an Aimpoint PRO if I had to choose NOW.

Thanks -

I have an aimpoint pro. Great choice. Given your choice of (future) optic, I'd go fixed A2 style. It's bomb proof, dead reliable. Nothing wrong with the railed gas block, but i'd go with the standard FSB.