For many venues, (depending on the genre, and the volume of the rest of the band), 100 Watts is more than adequate, if you have efficient, and properly positioned speaker cabinets.
For just plain more volume, you get more bang for your buck by increasing speaker displacement, (diameter, and cone movement), by adding identical speaker cabinets.
But, you are intending to make use of two distinct signal chains as a way to obtain a certain sound, and not to achieve greater SPL.
My personal opinion is that it is unnecessary expense and hassle for little reward.
At least you will be using identical speaker cabinets, (I hope).
For just plain more volume, you get more bang for your buck by increasing speaker displacement, (diameter, and cone movement), by adding identical speaker cabinets.
But, you are intending to make use of two distinct signal chains as a way to obtain a certain sound, and not to achieve greater SPL.
My personal opinion is that it is unnecessary expense and hassle for little reward.
At least you will be using identical speaker cabinets, (I hope).