It is a very difficult choice. "Flying solo" means that you are rewarded more for your efforts than in the daily grind of a regular job, but you are really at the mercies of a random market place which can change over night. I can only put myself in Dave's position (which is not easy). With an income independent of your web presence, you can afford to be objective and critical in reviews, but when a manufacturer or seller realises that the reviewer is dependent on freebies then they start to lean on you. I would give the comparison of car magazines. There are very very few magazine which give open opinions on new vehicles, the rest have to suppress or diminish potentially horrible faults in order to remain in favour with manufacturers.
Another problem is that, above a certain workload, the admin takes over from the job itself. I am a freelance design engineer, but should really be called an administrator, marketer and manager because that takes up 70-80% of my time (which I hate). Ideally I need another person to do that, but then that's a fixed overhead, and ties you down in a job that you do because of the freedom. I understand from various videos, that manufacturers and sellers are keen to give Dave stuff to review (which might well increase the overall audience) but he would prefer his independence. Something I can identify with. Bigger is not necessarily better.