I wear size M/L BDU's, and I have two pair of 3 year old military woodland camo to compare against.
I have two pair of MARPAT trousers.
The M/L pair made by American Apparel Inc. are a bit tight in the waist, but still do fine:
It might be the elastic is a bit tight.
They feel like a pair that were made on a Friday.
I usually tie the pant leg draw strings on my BDU's, and let them rest on my boot tops, but because MARPAT's have no draw strings, this presented a problem with the "long" length in that using blousing straps might make the pant leg a tad on the short size, so I bought a pair of M/XL MARPATS.
The M/XL's are made by Propper International, and like all Propper clothing, they fit great.
They are closer in fit (in the waist) to the older style BDU.
They are snug in the waist because of the elastic, but there is more give to the elastic.
There is plenty of length for using blousing straps if so desired.
If you are planning on blousing, go with one length longer.
If you are planning on letting them hang out of the boot, get them in the length you would normally.
Jay