Kuba.g you forget the most important: that roamline rate of 0.89/mb covers 85 non-European countries!
most of these important countries are top leisure+business destinations such as Japan, Brazil, Argentina, United Arab Emirates, Qatar, Pakistan, Indonesia etc which aren't covered by abroadband!
have a look and compare:
https://www.roamline.com/countries-1
http://www.abroadband.com/en/GR/countries
another also important parameter, because roamline uses KPN roaming agreements, their simcard can be used with all local networks in each country, so there is wider signal coverage!
abroadband just uses 1network per country, mainly of Vodafone group.
concerning the 0.39/mb rate within Europe, the rate is excellent, especially for higher daily or weekly data amounts over 60mb!
for Canada, United States and Switzerland the rate of 0,39eur./mb is just the best current choise in the market.
i have also been informed from roamline customer service that as of next month, they will also introduce data bundles for higher data usage within European Union, where the price per mb will be below 0.20eur per mb.