Hi @icme!
Yes, we are currently at 2x limit. DTS looks good so far in production, so I think we could go to 6x relatively quickly: in a couple of replica versions.
There is one non-technical issue that we discovered with Motoko that needs to be resolved before we go to 6x.
The issue is out-of-memory handling in Motoko. Currently the low instruction limit for updates acts as a safeguard against Motoko canisters hitting the hard 4GB limit. When the memory usage of a Motoko canister increases and reaches 1-2GB, then update messages start failing with out-of-instructions errors. At that point upgrading the canister is still possible (because upgrade messages have higher instruction limit), so the owner of the canister can salvage the canister and its data by upgrading it to a new version that uses less memory.
With the 6x DTS, the canister will be able to grow to 4GB with update messages. Once the canister reaches 4GB and updates start failing due to out-of-memory, then upgrades will also fail. This means that the canister becomes stuck without any fix.
I have an idea to solve this problem by introducing a “freezing threshold” for memory. It would be a canister settings parameter with the default value of 3GB. When the canister reaches that limit, then updates start failing, but upgrades continue to work. The owner of the canister would be able to increase or decrease the parameter.