1) is it worth the effort - only you can answer that - the new widgets area is fixed 3.4.3
Java rotation of the header image was dropped in 3.4.1 but back in 3.4.2. I say look at all the things that are mentioned in the upgrade notices for 3.4.2, 3.4.3 and 3.4.4 and base your decision on that.
2) customized changes to code: I always recomment doing the minimum number of these and seeing if you can do it in the options instead. With the new center column 'The LOOP' option, lots of code changes can be added as options now. This way you can upgrade with no hassle.
I would suggest that you download 3.4.4 and your current 3.4.1 and do a comparison of the code. there are packages that will allow you to do this (on the MAC, 'TextWrangler' is excellent - you can open two documents and have it find the differences...and copy one to the other!)
If you choose to upgrade, you will get one other benefit, you have the oppertunity to document all those changes that you made t the code so you won't have this problem in the future.