I don´t think it´s really all that weird an idea... with the OP reflector the spot is pretty much the same as the pattern of the pellets... spill is maybe not super on the tiablo but reasonably bright to ensure overall visibility. Just point the beam at what you intend to blast...and Voila -both aimingcapability and lighting...
However I would definitely considder the Lumapower MRV, due to it´s separate batterycompartment, might be easier on the light when it comes to recoil.
The whole point of the Tiablo is throw - a relatively tight beam and there isnt that much difference between the OP and SM reflectors at shotgun ranges.
If your planning to loose off a shottie at something, you need to illuminate the target and have enough flood to track it if it darts left or right and a tight beam will not help here.
You also need to illuminate the background so you can see what is behind what you are shooting at so you dont let fly at something you shouldnt and you need to be able to ID what you intend to squeeze the trigger on.
I would say the T8/9 would probably be too tight thought the range for shottie is not a problem in terms or max engagement range you would ordinarily expect to engage and despach quarry at.
I would be interested to know what quarry you are intending to illuminate and take on with a shottie at night with. I have considered using the A8Q5 on a rimfire in support with a much bigger & dedicated shooting lamp on a dimmer. The dimmer gives you the ability to get retinal eye reflection and locate whislt the bigger output allows you to go further out to id and ensure a safe backstop etc.
I would not consider the A8/9 adequate for rimfire and I am even undecided on using on an HMR.
I would imagine the bulb is emitter is capable but the cuircuitry perhaps wasnt built with this recoil in mind especially long term