Dennis Smith is your guy, no disrespect to Larson intended. I have seen extensions he installed where the joint was totally invisible, even after his showing me where it was. (541) 483-2182
I also think Dennis does great work. But with any wood extension, you can tell. You may not see the seam, but the grain differences will give it away everytime. You can get close to matching, but never perfect.
Mark is able to blend the grains and does great work also.
Either way, both men are excellent!
Best!
Greg