A new element was added to the bitcoin scaling debate this week when the developer team behind startup Purse announced the launch of a testnet to trial its scaling solution, extension blocks.

Purse had already presented the ideas behind extension blocks in a blog post earlier this month, but the testnet will allow users to interact with working code for the new technology, available through GitHub.

So far, the launch seems to have galvanized early supporters, drawn to the way that the proposal would separate the block size from the network’s consensus rules, essentially allowing peers to set their own version of the limit.

BitPay CEO Stephen Pair, for example, announced that his company would be participating in the technical evaluation of the testnet, and gave his backing to future implementation of the idea, contingent on testing.

“If it holds up to scrutiny, we may support activation on the mainnet,” Pair wrote in a Medium post.

For those who haven’t been following, proponents of extension blocks see it as a way to scale network capacity that will appeal to various factions in the current debate, thereby building consensus among developers and mining pools that have previously been at odds.

However, support for extension blocks is not universal.

In a post to the bitcoin-dev mailing list discussing the Purse team’s initial extension block specification, Core developer Luke Dashjr assessed that the proposal as one that would “creat[e] a lot of additional technical debt”.

Johnson Lau, author of an earlier extension block proposal in January, also warned of possible security risks:

“Logically speaking if SegWit is not safe, this BIP could only be worse,” Lau wrote in an email to the bitcoin-dev list.

Disclaimer: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in Purse.

Colorful blocks image via Shutterstock