I saved for a year and a half for my 12-24 and thought that my LBA was done. It was my best lens and I was VERY happy with it and it was glued to my camera for a year. I happened across a used 21 in mint condition for a very good price on a used camera website (pictured [that I never looked at] with serial number). After thinking about it for at least 6 to 8 weeks I finally ordered it - I figured a small prime for landscapes would be a very nice finishing final touch. But a 31 Ltd showed up (it was the lens pictured with the s/n) so that is what the store sent.
Now I would not have bought it out right for myself - as I did not think that my skill level was up to the lens. However, I do have to say, that the 31 has been VERY enjoyable to use. I stitch a lot with it. I really - really like it!! It feels wonderful - like the precision instrument that it is. I would almost say it has make me a better photographer - since I have been trying a lot of different things with it. I am an engineer, and the build is everything, everyone says it is and more. It produces wonderful images - I look at them and say - did I really take that, or was it the lens fixing my deficiencies....
When I travel on business, rather than take my 12-24 and 16-45 - I just take the K20 and 31Ltd. That's it. For a limited amount of space, that's all I feel I need. I can make anything work with it.
So, if you can afford it, and can splurge - yes, it is worth it.
My LBA is in remission. I am really done. I really have all that I need - and what I need to do is go take more pictures, putting these tools to what they were designed to do - capture wonderful images - and improving my skills.....