Is It Wise And/Or Acceptable To Cut Mint Sheets Into Blocks?

OK, so here's what I've found researching these over the course of the day. ebay is showing 2 that have sold; both plate blocks of 4 Poland (#909) with the word "POLAND" in the margin. One plate block of 4 sold for $6.50 with .95 cent shipping, the other for $8 with free shipping. Both still come up in the search results.

Obviously not all of these sheets that I've acquired are as popular as the overrun nations series, and who knows how long the sellers had to list and re-list these blocks before they sold.

Again I would never split these sheets up now, but it is interesting to note that there is still a market for some of these plate blocks. As I was doing other research on these I had read that plate block collecting was on the decline, and less and less collectors are interested in them, thus driving down the price.

And as stated I before acquired these for free, so even if I sold the sheets for $1 I would turn a profit, but that's not my intention. I'm not a dealer, and I'm not getting back into collecting to make money. I'm doing it because I love the stamps!

But thanks again to everyone for the help!

Just like anything else, this is about supply and demand.

On the supply side…
Few proof sets were issued in quantities around 3 million; most were issued in quantities of around 1 million. The commemorative stamps you are talking about were printed in quantities that exceed ten times those amounts; print runs of >100 million were common.

On the demand side…
Full sheets of postage can be difficult to store/display and mount; so many collectors do not collect stamps in this format. The marketplace is flush with these stamps being offered at or below face value. Some folks don't even want to deal with them since they would have to cover a envelope or parcel completely with stamps to make up today's rate.
And of course proof sets represent the pinnacle of 'condition' for a coin, a full sheet of stamps is not seen the same way. (But it is true that classic era stamps multiples command premiums but this is due to rarity and not 'condition'.)

That said, there are a few plate blocks/plate numbers that might make some off the sheet you have a worth a bit more than the others. You would have to get a Durlands Catalog and look those up. And the folks above are right, there are some screwy things going on with some ebay sellers of 'plate blocks'; there are a handful of sellers who offer a big stack of cheap plates that APPEAR to bring five to ten times face value but beware of these listings.

But it was good that you asked this question; I think many of us have a moment of doubt when we break down a full sheet of stamps. But in my opinion and in this case you are not committing any sins in doing so.