How did you go with the Selphy?
Did it work OK?
It worked well and people were very happy with the results. The only significant issue was print speed, as expected. We got fairly far behind generating prints when things got busy about halfway into the event, and people were waiting 20min for prints by the end. Some even left without picking up prints which is a problem (we left them at the zoo venue for later pickup, but many probably just went to the web and abandoned the prints).
In terms of set-up, I had a volunteer assistant sitting at the laptop picking the best of 2-3 prints per group and running the printer, and I just kept shooting in the next room with my 6D wirelessly tethered to Lightroom on the laptop (via the Canon WFT driver and EOS Utility running in the background). JPegs showed up on the laptop within a few seconds, and that worked smoothly all night without me having to think about it.
In all, we printed 120 photos in just over 2 hours, so doing the math you can see the printer ran full out for the entire time. We're considering setting up 2 printers on the same laptop and queuing up 2-3 prints and then switching over in Lightroom for our next event (photos with Santa). I can see the utility of buying a bigger/faster printer if you did this all the time (or for print sales), but this works well enough at $80 a pop and $.30/print.