Not sure what TBN has planned (it sure has been a long time in the coming). But, If I were running this website, I'd seek out the truly experienced users, and/or users with many hours on their machines to write reviews. I would entice them to write with good old fashion hard cash, say $50 for 75 words of wisdom. To pay for this, I would sell ad space to manufacturers, divide the tractor reviews in sections by manufacturer and implements by type, and have the user watch an ad before they can access the reviews. To keep it from being annoying the user would have the option to skip the ad. I think most of us like watching short, informative demos of equipment, at least one time anyway. This could be far more efficient than having the user wade through post after post of new owners who love their first-ever tractor with just 50 hours of experience in order to find the one or two guys who really know what they are talking about.
Further, I'd try to broker deals with printed publications that write reviews and obtain rights to reprint, or link to their sites for the reviews.
Similarly, in the specifications section, I would think that manufacturers would be quick to offer up their specs if they got some "press" out of it when users went there. Certainly, links to the manufacturers' websites is a very easy implementation and I don't think you even need their permission. I'm not sure why this hasn't been done already.