Very good post Michael.
There is another con I wish to add to the list if I may.
When I first started I did some sub for subbing. I'd say maybe up to 50 or so subs. Now some of the people I made a deal with would sometime sub me with one account, and the deal was for me to sub them on another account (their main channel). These people get their subs, and forget about the other channel. Flash forward a bit and YouTube starts closing "dead" accounts and you get losses in your subscriber count.