If the cab you have been using is is the STL-10T, chances are you have been pushing it too hard.
While I understand the desire for a light cab, you need to factor in your volume requirements.
I think the Genzler Acoustic Array line would be a really good choice for upright.
Here are the specs from the series IV AI manual
View attachment 7417144
The Genzler BA10-2 is rated 300W RMS with a 97db 1W/1m sensitivity rating. Weight is 19lbs. With one BA10-2 you will probably be at about the same place were with your Genz Benz cab...pushing it a bit over the edge. Calculated SPL at 300W is 121.8dB
If your GB cab is the STL-10T, it was rated 200W RMS and had the same sensitivity rating as the BA10-2. Calculated SPL at 200W is 120dB. So the Genzler should be able to play ever so slightly louder.
A safer option would be a BA12-3. This cab is rated 400W with a 98dB 1W/1m sensitivity rating. Weight is 35lbs. Calculated SPL at 350W is 123.4dB
The BA210-3 or BA15-3 gives you even more headroom. Both are slightly larger, but about the same weight.