We have an issue where we had both widgets.com/Blue_Grommets/ (upper case) and widgets.com/blue_widgets/ (lower case) with a PR4 and PR1 respectively, so we 301'd the upper case respectively to avoid the duplicates. The upper case had a load of backlinks and ranked in top 10 for loads of competitive keyword SERPS; the lc one didnt have any and didnt really rank at all.
Now we have lost rankings across the board, consistent with a PR 1 or so.
So perhaps G is not allowing link strength and/or PR to be passed via a 301 redirect between internal pages?
Any merits in this theory? If so how can it be reversed? Right now our Upper Case page has gone supplemental and my understanding is that once its gone its gone?
Well - I would have 301'd the PR 1 onto the PR4 - NOT the other way round.
Going back to the original post,
We have had nothing but success with 301s. However, we first try not to change the filenames at all if we can help it. Then we aim to 301 the minor on to the major so to speak.
The fact that you are a blog may be significant. None of the sites we have actively used 301s on are anywhere near blog like. They are real world companies. We also don't seem to have the supplemental issues that most have (in general - with notable exceptions).
Does that mean by removing the 301s, you have you created new URLs, containing duplicate content? - so google takes them and indexes them into the main index... but in a few days it will decide that it is duplicates of the other URL and you might find both URLS in supplemental. As you say - it will be interesting to see ho December plays out for you.