Yes, ability to use a handlebar bag is a really good point!
I have bar-end mirrors on my roadie and my old touring bike so very familiar with knocking them regularly. But, the LBS says he cuts about 1.5" off the handlebars when he installs barcons so they won't extend much further than the stock bar. (don't need the extra length anyway).
As for getting used to the shifting position...I have 4 other bikes and each has different shifters so it's inevitable that occasionally I'll reach for the downtube or the brake hoods or elsewhere. So, hopefully I'll get used to the bar-ends too.
Thanks for the opinions. I'm not 100% decided yet so happy to hear from others.