Thanks for the comments everyone...it's great to get feedback from one's peers.
And Carole, understand that you are asking questions of another newbie.[
] With regards to the "fatter" profile. I prefer it; I don't like the true cylindrical Slimline. Yes, the clip is tight. I use Berea Hardwoods kits, and they are VERY tight. I would consider a pen defective if the clip revolves on it. No it is not more difficult to clip in to a pocket...there is plenty of spring in the clip.
The thing I've found critical is that you don't want to make it too "fat" or the clip is deflected too much and that detracts from the appearance.
I use a digital caliper when I'm turning it. I turn the upper barrel to +/- .045 then sand it to final size. I've found that about .042 is maximum diameter for the upper barrel before the clip starts deflecting too much for my preference. Again it's a matter of taste.
I hope that answers your question...if not then ask again. People here have taught me, so I'm happy to share my limited experience.