All these details and more in our technical paper! In short: SMERF training takes much longer, SMERF rendering is nearly as fast as 3DGS when a CUDA GPU is available, and quality is visibly higher than 3DGS on large scenes and slightly higher on smaller scenes.

https://arxiv.org/abs/2312.07541

Is it possible to use zip-nerf to train GS to eliminate the floaters.

Maybe! That's the seed of a completely different research paper :)