I love wool blankets and own several, which I have employed in the field. I use the tan emergency blanket dubbed "the loincloth" (at 6'4" the thing is fine for covering me from shin to mid chest" as my display blanket, on my knapsack and as a cover to my bedroll in the field. It is light, rolls well and looks great. Unless one is 5'7" plus or minus an inch, I would not recommend it for anything other than summer use to keep the bugs off yourself.
My farby blankets of choice are my 6 pound 100% wool Filson in gray black plaid and a 5 1/2 pound 100% wool 1870 Hudson Bay red with black stripes. These are warm blankets, which cover my large frame well and are large enough to wrap myself top and bottom. The Filson is pricey, but I got the HB fairly cheap, $55-65ish.
I also have a 100% wool white with green, red and yellow thin stripes in a box pattern made in Canada blanket from around 1900. It is a great blanket, lighter than the Filson or the HB but almost as warm as it is very large, nearly covering a king sized bed. This was also in the same range as the HB.
My next blanket will probably be the Sekela issue blanket.
If it is cold, I do not care if the blankets are exact for the period. For any campaigning event, I will not use the warmer non period blankets, but at large events with a correct cover blanket I have no trouble.
As JS pointed out, a good Great Coat makes a world of difference.
All that being said, if it is cool or cold and everything you own is dripping wet, expect to not get much sleep.