I did both. I conducted extensive research and joined a recruiting site. I used it as a resource. Can you get the same information on your own than you can from a recruiting site? Of course you can. It's not a make or break. Is it an added resource. Showcases and prospect camps are also resources. Travel teams are resources. But once again, if you do not do your own research and do the heavy lifting in the recruiting process, it doesn't matter what recruiting service you use, it wont do much for you. It's just another resource.
Just remember, D1 is where the best talent is, but it doesn't mean D2, D3, NAIA, or JCs are less competitive. Among the things to consider is how important it is to be able to watch your son play in person, for both of you. If that is a priority, than your list will look vastly different than if your priority is playing only for top academic schools, or selecting a school where your son will have the most playing time. First, you have to determine what are your son's priorities in selecting a school. Some players will be happy at any D1 that gives them an opportunity, whatever corner of the country its located in. Others would rather play for an NAIA school in their backyard than play for a D1 on the other side of the country.
Have fun with the process. Somewhere there is a school with your son's name on it. And when you pitch a no hitter, hit for the cycle in a game, are spotlighted in the local paper, and make your school's hall of fame, it really doesn't matter what division your son is playing for. Your smile wont be any less wide.