Something like this is always difficult. As I look back, I had many job offers at one time and can't help thinking 'what if?". Judging from what others have said about your work, I suspect you could rise fast in that company and find the work challenging and rewarding. One thought does concern age. Working independantly, an injury could turn you into a welfare case overnight. With a company there could be duty adjustments and/or insurance. Lotsa things to consider. Good luck.
"Folks is funny critters."
Think for yourselves and let others enjoy the privilege to do so, too. ~Voltaire