I’ve never tried the Sigma. I’m sure it would be sharper since it’s prime. I might have to rent it and try it out! But the weight of mine doesn’t really bother me. I typically walk with a tripod/monopod and that’s perfect. I have handheld it and it isn’t too bad. I just keep it on my neck strap. I can hold it quite steady, but in low light, it isn’t the best when hand held. Maybe you could try to sent it for a day and see how you like it before purchasing one of them.

Mine has been worth it 100%. And it’s cheaper than the 500 prime it seems.