Actually ANSVR is based on astrometry.net, and it does accept RA/DEC hint and search radius if you provide them (center_ra, center_dec, and radius)
astrometry.net is very fast when it works too. However my current experience is that the downsampling parameter plays a substantial role in success of solving and speed of solving (between 1 second success and not solvable). I think the star extraction algorithm might have some dependence on how bloated the stars are.
I have compared with PlateSolve2 a while ago. It was hit and miss between the two.
Anyway, if it is not too hard, I'd prefer to see the astrometry.net hint used by SGPro too. But now that I know that the hint is not sent, I wouldn't try to put them in until they are supported.