If you go for refill you can use these megatank inks indeed but please be aware - Canon does not tell you - that they ship different quality inks with different megatank printers. The best inks in respect to longevity are the bottled inks for the G620/650 model and forget the inks for the model series G2000/3000 , pricing is somewhat similar but the longevity performance is vastly different. The inks for the G620 are the same Chromalife 100 inks as listed above by
@stratman in posting #2 and used in these cartridges.
with these G620 inks - or with the genuine cartridges for your printer using the Chromalife 100 inks. No Amazon etc substitute of these cartidges can match the Chromalife 100 performance.