When Amaysim rolled out its 4G plans last month, one of the annoying features was that the amount of data on its $44.90 Unlimited plan dropped from 5GB to 4GB. That's no longer the case — you now get 5GB with that plan, just like the old days.
The data volume has also been increased from 6GB to 7GB on the $54.90 Unlimited plan, and from 1.5GB to 2GB on the $29.90 Text plan. In this context, there doesn't seem much reason not to switch from the old Unlimited Plan, which had remained available for customers who figured they would prefer 5GB a month to 4GB a month. Sticking with the old plan leaves you on the 3G network.
When the 4G plans launched, Amaysim told us that because it was now calculating data per KB rather than per MB, many customers would effectively use the same amount of data. The per KB charging remains in place, so this seems a better deal all around.