Personally, I don't really understand wanting to move up. You have a 4x5 and 8x10 setup and a sweet scanner (I know, because I have the same one). To me, it sounds like you are set. And if I remember correctly from older posts you acquired this scanner in the last 6 months or so. It surprises me that you would want to trade it in this soon.

That being said, I have to admit that I don't shoot black and white, so the allure of contact printing is not the same for me. Don't get me wrong part of me wants to make large black and white contacts, there is a simple elegance to the process, and the results can be amazing. But I think 8x10 is amazing too. It's a good mix of portability and quality. The equipment is easier to find and cheaper, and there are still film options, including color neg and transparencies.

But I guess the my real concern is that you would be trading in some of you 8x10 stuff and your scanner. I know from experience (not much though as I am not much older than you) that every time I trade in equipment for something 'better' I regret it. Happened with my Leica M6, and my first Mamiya 7ii. I will never be able to get such a deal on a Leica again, i miss it. The only time I have sold equipment and been happy was when I sold my 5DMkII setup to fund my DPL800. I have no regrets, though it has been less than a year so there is always time for regret to set in, though I don't think it will in this case. I guess what I am saying is by all means try 11x14, sound like a lot of fun, just be careful about selling off gear that you will want later. Or hell, just get serious an go for 16x20 or 20x24....skip all that junk in between...