I thankful to you for sharing this because I have not yet use ipad pen. Your information contains many of the tricks for using it in a very right way. Also it is much labourless in use.

I have a targus stylus. It works well. They kept selling out at best buy around Christmas time when they had them for sell. I was finally able to grab one a week or so after Christmas. At reg. Price :-( lol. Glad I got it though. My only thing now is making sure I don't loose it. This a $20 pen..lmao

I have a Pogo Sketch stylus and using it intensively for taking handwritten notes.
It was not bad but after five months the tip became softer than it was and it happend to me to touch the glass of the screen with the thin plastic ring that covers the metal body of the stylus in the proximity of the conductive sponge tip.
The conductive material accumulated also some dirt that can not be cleaned any more and consumed on one side more than the other because I tend to write with it always in the same position due to the clip that feels confortable when not against my hand while writing.
It is a good pen and for sure the one that I would recommend for starting but now I am searching for something else. I would prefer it slightly heavier and longer, half way between the Pogo and a normal pen.
The thickness of the tip is the right one, it allows good touch sensitivity on the screen while not being very thick ( as most of you probably know, the current iPad technology doesn't allow small tips, there is a minimum dimension of the tip that can be detected ). It is well thicker than the normal pen tip and when you start it takes a while before getting used and being precise but you get there with some practice.
In my experience there is absolutely no need to keep the stylus vertical. I angle it and it works perfectly. I use it naturally in the position that I would use a pen.
The pressure required to write is comparable with the pressure that I would put on a ball pen while the pressure required to click or scroll is slightly higher than the pressure that I would put on my finger in order to do the same.
I have no idea how the stylus would work with a screen protector because I do not use one. In five months of hard using my iPad ( more than 8 hours a day, at work and at home ) my screen is still perfect even when I look at it in reflection, under very bright light.