As far as im aware they were issued later in the war but not in great numbers so the wool trousers were alot more common same for the M43 jacket with not so many issued the M41 was still dominant, but youd better wait for a US geardo to comfirm that 
M43s were issued to be worn over wool trousers for extra warmth. As a rough guide, issued from Market Garden and became more prevalent in Winter '44.
M43 jackets were issued to replace the M41.
http://en.wikipedia.org/wiki/United_Sta ... 43_Uniform
They really are not as common in NW Europe in infantry divisions as you might expect. The jackets did see some use late on but the trousers are uncommon. Some units didnt get them until almost the end. The bloody bucket div 28th didn't have them in the Huertgen.
This was not the case in Italy where they were seen much more.
Double buckle boots were usually worn with the M43.
aka Stigroadie
AFRA
better by design
"Truth is a shining goddess, always veiled, always distant, never wholly approachable, but worthy of all the devotion of which the human spirit is capable. "
Yeah the Gaitors are usually only worn in conjunction with the roughout boot, because of the low sides on it (stop sand and debris falling in)
Buckle boots are roughout boots with the extension on them and I imagine a lot quicker to get off that gaitor'd up boots
