Framebuilders - Custom vs. Stock Gain

I own a Reynolds steel frame on my Jamis Aurora Elite that fits pretty well on my touring bike and I mostly love it. Yet as I put on over 70 miles, I am aware that the sizing is not a perfect match -- although not too bad -- so I was a bit more curious about what people think about spending the extra dough to get a custom made steel frame that is exactly my size. What sorts of advantages do you think I'd see/get? I mean off the top, I'm thinking a very, very good fitting bike would be more comfortable in the saddle over the long run, less wear and tear on my body, and who knows -- perhaps even a performance gain.

Anybody have any thoughts on this? Did switching over to a custom sized bike frame make a notice-able difference? Any down side other than price?

Toddles- Custom bikes are usually seen as a fit/comfort benefit. Are you able to get a comfy position on the current bike without being so far in it's adjustment range as to effect handling (like the seat all the way back on it's rails or a super short/high stem)? If so then the custom bike will not improve the fit /handling much. How about the braze ons? Do you wish that they could be better placed or are some missing that you'd like to have (like double eyelets, pump pegs or cable adjusters)? Is there an issue with the handling when fully loaded (like shimmy)? How about tire width/fender clearances? What about travel ease, S&S couplers?

Don't expect a performance gain with a touring bike, other then load capicity or fit. But ease of use and set up might be better depending. Andy.

My one-off touring bike is pretty non standard to handle the pannier load
without undesired flexing.. but it weighs more in the process..