Ah, great, I just wasn't sure what you meant with ceil(count/2).
It's not worth implementing when VLEN>=DLEN, beacause then you can replace all of the uses were you'd always get an atvantage with unrolled LMUL=1 instructions.
So I don't think it will be common in ooo designs, since they usually have smaller vectors.
It's only not worth it if software indeed consistently does the LMUL=1 unrolling. Which I suppose most will, and vrgather with LMUL>1 will be roughly dead-on-arrival, but who knows.
It's not worth implementing when VLEN>=DLEN, beacause then you can replace all of the uses were you'd always get an atvantage with unrolled LMUL=1 instructions. So I don't think it will be common in ooo designs, since they usually have smaller vectors.