Yes, whatever is removed ought to be available elsewhere.
+1It looks like it won't be easy to get a concensus on this one.
For my part I like the idea of moving forward and eventually using all of the factory cab slots for a UR cabs that cover all of the same ground as the current stock cab lineup (wherever possible of course).
I'd like to echo others comments regarding making the current stock IR's available to be used in user IR slots. I remember reading that there were/are some copyright issues doing so as there are IR contributions from Redirector and Ownhammer. Hopefully there's a way around this at some point.
If I had to pick stock IR's to which I'd tike to retain access I'd have to say: the 1x6 oval, the 1x12 G12H30, the Bassman 4x10, the HiWatt 4x12's, the Dumble 4x12's, the 4x12 green mix and TV mix, and all of the bass cabs..
In the meantime there are some who have suggested dropping the Kathleen IR from factory slots as they are all readily and freely available online. This seems like the solution with the least impact on the many users still utilizing the factory cabs.
IMHO, YMMV, and all that.
I'm using some OH & Redwirez IRs and some UR that you replaced in factory cabs, So it's hard for me to pickup, because I just forgotten which one of them was really good or wasn't for my needs, I think the best thing for Mark I &II owners is adding two more factory cabwith the new IR mixes. These two mixes are quickly becoming my go-to IRs for many amps. So I'm thinking we should replace two of the factory cabs with these new mixes. Suggestions?