Razer
YTtalk Mad
I agree with the points you've given but I don't think sub4sub works... I tried it along time ago thinking it was one quick way to gain subscribers... It was GREAT it worked I got 400+ subs in like the space of two weeks BUT and it's a big but I'd then think mint, now when I upload I'll have 400+ views... sadly I was very very wrong I got a hand full of views. So basically I just had a cool number of subscribers but nothing really to brag about because I wasn't getting any views and people didn't care about my content so I think sub4sub is the most pointless exercise to get subscribers in the whole of the world, just get subscribers through promoting your videos because 10 subscribers watching your videos consistently is better than 5-10 views with 400+ subs.