Are you asking how well it would work to turn a rig that currently mines Ethereum to one that mines 0xBTC?
Interesting question. A lot of Ethereum miners will need to switch to another algorithm when Ethereum 2 comes out.
In the 0xBitcoin project, we anticipate picking up at least some of that hash power.
If you have specific GPUs in mind, please tell me.

Hi! 0xBTC/ERC-918 tokens are mined with the SoliditySha3 algo (an implementation of Keccak256). So, your hashrates will vary from what you'd see using an Ethereum miner.
What sort of hardware do you use? Unlike traditional Ethereum mining it is not memory-hard but is very computationally (GPU core)-intensive. So the way to go is higher GPU clocks, lower memory clock. nVidia hardware has been the most optimized for and is the best suited for the job.

AMD hardware gets respectable hashrates too- but it's probably more profitable to mine a memory-intensive algorithm with those cards (Ethash, Cryptonight variants etc.) and then buy 0xBTC on one of its listed exchanges, Uniswap, DEXes etc.

Its implementation means that as/when Ethereum makes its move to Proof-of-Stake consensus, tokens will remain mineable.

The latest software for mining 0xBTC/ERC918 tokens on nVidia, AMD and CPUs can be found here:
https://www.reddit.com/r/0xbitcoin/comments/8o06dk/links_to_the_newestbest_miners_for_nvidia_amd/

Multiple miners have been developed for the job and support nVidia, AMD, single or multi-GPU configurations and multiple OS'es. At least a couple are under continual development, too. Feel free to ask in here or in the Discord server if you need more info. Hope this helps!