Does anyone have knowledge as to the quality of the Ritchey Logic lines? How significant is the difference between Ritchey WCS, Pro, and Comp?

Which parts? handlebars, stems, cranks, wheels, seat posts?

I can tell you handlebars only have a difference in weight. Quality between all 3 is the same.

AEQ .... I am interested in choosing a good quality Handlebar and Seatpost. I am drawn to the Ritchey Logic Pro and Comp lines by the price points, but will not spend money on something that I would be compelled to replace due to performance or quality issues. I believe that the choices in drive train components is critical to get right from the start and that the differences in reliability and performance are well documented in the Shimano line as well as SRAM, but when it comes to handlebars, seatposts, steams, and to a degree headsets I am not certain if the relationship between price points and the quality and performance are well aligned.

It's all durable. You pay for better finish and less weight. I have a Ritchey Comp seatpost and two 4-Axis road stems.

it's good solid stuff. i use their stems mostly but i've used a few of their bars as well and it's all good quality.

seatpost: thomson or deda for set back.
handlebars: deda or FSA
stem: whatever floats your boat.

Ritchey handlebars are nice and cheap, but IMO the ergo bend they have is really horrible. The design of the bend is really a matter of if you like it or not.

I have a Ritchey frame, post, stem, bars, and headset. All have been flawless. Ergo bend on the bars feels awesome to me. I've got a pro/WCS mix -- all good stuff.

I like the WCS bars and the 4-axis stem that I have on my litespeed.