Orion indeed does sell the 25mm Aerial flares ... BUT WM and other sources never seem to carry them anymore in stock and therefore you always need to 'special order' them ... and the prices have essentially doubled.

They are not parachute flares but the same 'rockets' as in the past; although the geometry is now different but still can be used in a 25mm gun. They are now smaller in diameter and longer (the 'shell' now sticks out beyond the end of the 'gun') than previous and the only geometry that is 25mm is a small section that comes in contact with the breech of the flare gun - so 'most' of the flare casing doesnt come in contact with the barrel of the 'gun'.
With the 'new' geometry its highly suggestive that previous shells expanded when fired and broke/burst the barrel of the flare gun. The endpoint question therefore: is this new design a design inspired/caused by lawyers or is it fully equal to the 'old' design -- wont know until I fire off a few when my current 'new' flares expire (on July4th of course).

Since the 25mm give twice the light and twice the height Im sticking with 25mm and not changing down to the anemic 12ga. aerial flares.