[davidtheprof]

for the European cities, with the new EU roaming rates, a national sim (I used O2) is not too expensive and more reliable. O2 and Vodafone have good EU data roaming packages as well.
for Piranha you have to call them to switch primary number. Not sure why outgoing didn't work earlier and does now.
Piranha is call back, not everyone likes that. But overall it works well at low cost.
Messing around with sims and mifi was most exciting part of cruise... we were 'reluctant cruisers', part of larger family group celebration... Ports are interesting, and get your own guides, not the ship tours.