This might be a stupid question, but what does 'custom implementation' actually mean? is it that Bismuth was created from scratch and it's not a clone?
new algo, wallet and node made in Python, I'll bet you won't see anything like that on Earth. Really unique stuff to the point of each pool having its own custom miner. I've noticed yet another pool
http://bis-pool.net/ and they have their own miner of course so that makes three