Why not do it to one now, and keep the other for your layering practice. That way you get the best of both worlds and learn both techniques at the same time.
You can cut ash back to a bare stump and know for sure that you will get stacks of buds/shoots
I would personally be more aggressive with the root cutting on the ash if you decide to cut it back to a bare stump...and also bare root it completely
If you do cut back to a stump, you can cut horizontally initially and then cut on the diagonal once you see where the buds pop etc. Or you can cut on the diagonal to start with...up to you?
But if you do cut on the diagonal (when taking back to a bare stump), I would cut in the opposite direction to what you showed in your virt...if you are unsure what I mean, feel free to ask
Josh please only keep one for your layers and cut one back to a stump now! You will learn more in my opinion and it will be more enjoyable for you both
And 100% you won't regret doing so as it will be good practice for next year when I take you to get a few ash (that will be cut to a bare stump upon collection!) you will already know what to expect and have some experience rebuilding your tree
Not trying to pressure you though...your tree, your choice mate
Cheers, Dario.
What am I saying. Oh that's right these didn't cost me much so cutting 90% of the tree of won't hurt 
spewing, as I had my heart set on a couple of larger ones...so "bring on next winter!" 
I know what I mean, just can't seem to put it into words properly:palm: 
