I bought a Vintage Hot Stack Plus and put it in the neck position.
It is higher than the JB in the bridge and I can feel a noticeable drop in volume, so in the middle position, set lower it will be even more noticeable.
If there is a significant difference in output (with Vintage Hot Stack), then Classic Stack is definitely not for me.
If the Vintage Hot Stack is too weak for me, I think the Hot Stack® Strat (bridge version) would be a good idea. Dann Huff uses them and has great cleans.
Possibly Custom Stack Plus will be fine, but I suspect that the single coil nature will start to fade.