TL;DR: X-Adapter enable plugins pretrained on old version (e.g. SD1.5) directly work with the upgraded Model (e.g., SDXL) without further retraining
https://showlab.github.io/X-Adapter/
Until now, Generative Artists have been limited by the compatibility restrictions of the various Stable Diffusion versions. While there has a varied ecosystem of model available for SD1.5, SD2.1 and SDXL (and more) sometimes it can be difficult to find specific styles and subjects across all versions.
The X-Adaptor will solve this by allowing any Stable Diffusion versions to be used with SDXL as shown in the links above.
With this in mind, it's time to blow the dust off your old SD1.5 and SD2.1 models as we will soon be able to pipe them through SDXL. The applications are looking to be truly amazing, so i had to bring this article to let you all know!
read the full paper above, and check out the examples and you should see the potential this will have for us all.