Does this mean changeover's have moved up sharply ?
Should They ?
Buxvet
I think to advanced collectors all change-overs will be accorded premium book value (that's what the blurb from Charlton is saying) but whether that translates into reality is another story altogether. Remember that you are not the "average collector" so if you want to sell a rarer change-over you might have to brace yourself for a luke-warm reception of your note (to the less informed).
However, I believe you are wise in snatching up any change-overs you find, esp if you can get them from coin dealers who are caught napping! They will certainly be given their proper value eventually. It may take a year or so for the collecting community (shorter for the dealers) to catch on to these short prefixes (particularly the 37's). If your into this hobby for the long haul-- you can't go wrong.
Naturally a note's actual market value depends on what's "hot" at any particular time of year. So far (and I doubt this will change) but demand seems to go in cycles (maybe this is due to the near onslaught of one auction after another!) Its inversely proportional to what we see being sold (ie: if there's a lot being sold - demand and price sometimes goes down - few sold -demand and price goes up) like any market. As I'm sure you know it also depends on what dealers are seeing a lot of (whether you'll get someone interested), the press a note receives, and whether dealers deem it hot (it will "move"), if you need to sell in a rush (and you wish to trade or upgrade) etc.
These days everyone seems to be keen on O/T 1937's and DF's and certain replacements within the 1954 series (at most shows today) and certain MC's replacements, or good-overs (ie L/B EET) If you got what dealers are looking for-- then you can move it quickly.
There seems to be less demand for regular Multi coloured notes (69/79 $5/$20), Birds (unless they're the AUJ-AUN $2 or CB $5 Blue BPN, or the EVH noBPN $20) than common 37's or 54's (unless they're genuinely UNC). And yet Multi-coloured notes were all the "rage" a few years ago. In 2004 I got some very good deals on some UNC 37's (alas not O/T) but you could tell the dealer was happy to see them go. Now people are even buying the C/T signature series if they're in AU to UNC at close to BV. I've learned that it sometimes pays to "buck" the trend knowing that the cycle will return in favour of whatever issue you're concentrating on.
Bottom line is: do what you think will work. Your instincts so far have been "right on the money" and its unlikely they'll fail you when it comes to change-overs. Your posts reveal that you are a "sharp" collector with insightful thought processes regarding trends and what's collectible!