Well I went with removing the wood siding and replacing with hardiplank.

My reasons were the wood siding would eventually probably need repair in other areas too and then I'd have to re-paint that and by that time the whole house would probably need re-painting to match the patch.

The other reason was how often the house would need re-painting. The Hardiplank doesn't need re-painting nearly as often as wood does in my area. The sun is brutal on the wood. I changed the siding 3 years ago and re-painted the whole house including the garage. I didn't change the siding on the garage as it was in good shape and is detached (still wood siding). The garage needs re-painting again, but the hardie siding still looks freshly painted.

On if the painter can replace the rotting wood depends on the painter and his skills.