Do you consider ANY pen using a "cross-type" refill as "high end"? My answer would be NO.
So, to me, high end would be a rollerball or fountain (or "low-high" could be a Parker style using the 9000 refill).
The cigar pen has had some difficulties with the 9000 refill not fitting, it's just a little too tight a fit. Actually happens at the center coupler that screws on the transmission. The tubes on these require a 25/64 hole (.390625"). So, experience would indicate this to be a "minimum acceptable size" from which to start, for a Parker type.
You can perform the same "calculations" for rollerballs and fountain pens---that gives you a starting point.
Good luck in your endeavor!!
Ed
I buy the majority of my stuff from you, so which models do you suggest I look at?
I have never equated "thin" with "high end", so I don't have a "pat answer" for you Russ. The baron-sedona body is thin and yet elegant, and the pens come in a variety of plating choices. Thinner yet is the "new series", but the plating choices are limited. All of these are Berea.
I will spend some time researching this, this weekend and try to give you a better answer!!
Ed