It seems like the Bitcoin market and industry are rejecting Bitcoin Unlimited almost unanimously for the same reason: security and decentralization. Even miners are making the move to Segregated Witness, including the world’s largest Bitcoin miner and leading Blockchain company Bitfury.

Bitfury makes its move, selects SegWit

Bitfury is in support of SegWit. On March 26, Bitfury mined its first SegWit block with Bitcoin Improvement Proposal (BIP) 148 that contains the SegWit signal tag. BIP 148 is a proposal entitled “Mandatory activation of segwit deployment” released on March 12 introduced for miners as a way to signal their support for SegWit.

Shaolin Fry, the author of BIP 148, explained:

“Segwit increases the blocksize, fixes transaction malleability, and makes scripting easier to upgrade as well as bringing many other benefits. It is hoped that miners will respond to this BIP by activating Segwit early, before this BIP takes effect. Otherwise this BIP will cause the mandatory activation of the existing segwit deployment before the end of midnight November 15th 2017.”

Shortly after the SegWit (BIP 148) block was mined by Bitfury, Bitcoin India mined block 458716 containing the same tag, also signaling support for SegWit.

Previously, Bitcoin Unlimited supporters noted that businesses and users are in favor of SegWit because the solution doesn’t affect their profitability and revenues and that the miners are in support of Bitcoin Unlimited as the software guarantees high profitability for miners.

However, this reasoning is starting to be questioned by some of the largest mining pools in the market, including Bitfury and Bitcoin India.

Bitfury is in support of SegWit for many reasons, like every other SegWit supporting organization across the market. However, since mid last year, Bitfury has continued to emphasize the importance of off-chain scaling and two-layer solutions such as Lightning.

Also, Bitfury executives including the company’s Chief Information Officer (CIO) Alex Petrov have released various reports and test results of SegWit, as shown in Whale Panda's blog post.

Why Armory rejected Bitcoin Unlimited

Almost every business and platform operator within Bitcoin have rejected Bitcoin Unlimited due to security and decentralization issues.

Specifically, prominent Bitcoin wallet platform Armory’s lead developer Andrew Chow, better known as Goatpig, stated that Armory doesn’t approve Bitcoin Unlimited’s philosophy on allowing miners to vote whichever block size best suits the Bitcoin Blockchain.

Goatpig wrote:

“I disagree with BU's primary principle that the block size should be decided by user and miner vote. I disagree with the block size hard cap on the grounds that it is a magic number. Voting on a magic number does not improve upon this limitation. The only acceptable solution in my eyes is an algorithmic one. To imagine a technical metric is best discovered by popular vote is wishful thinking at best.”

More to that, a more obvious issue is that the Bitcoin Unlimited hard fork is contentious and dangerous in nature, as it will inevitably lead to a split chain if it is ever forked.