I finally was able to get my hands on a Sharpie | Pen. and it's great, I spent about 5 years without using that type of pens (fineliners / markers / felt tip pens / whatever you call them). I've been using them in both 15 lb and 20 lb paper and they are great. Bleeding is not an issue, the Uni Vision Needle get more bleeding than the Sharpie, and I don't write double sided, so I'm not really affected by bleeding.
The downside of felt tip pens is that they do offer some resistance to roll (well, to slide, since they don't roll), and it gets hard to write fast, so I only use them in low speed situations (like math class). I frequently find myself taking fast notes and then copying them again at a slower pace, resulting in neater handwriting and overall nicer look of the notes, and there I can use them, and the results are really nice.
Some people have complained about the blue one being too soft. It does feel soft, at least compared to other blue pens, but tolerable. I write on yellow paper most of the time, so it also gets a different look. If I do happen to stumble across a darker copy, I'll probably talk to Sanford and see if they can exchange them, but other than that, I'm fine.
I don't know about overall life since I haven't used as much as I use my Pilot V5 RT, which I'm guessing will reach the end of its useful life this week or the next one.
Stay tuned for pictures