I have had nearly all models since original. Use prior 9.7 IPP in home, 10.5" IPP for travel and 12.9 IPP for more work, bigger travel needs.
If you want portability and it doesn't have to be a more laptop replacement - mostly about screen real estate, then 11" is best. 12.9" today just give you that much more real estate. I'm waiting to try the new MKB with the 12.9 and pencil to see if this can really be something I can take ONLY on work travel. (assuming we all EVER travel again)