I have my 1008 clone setup with breather vents plumbed to the engine compartment on everything - including the transmission and transfer case.
I still avoid water and mud - I re-geared the axles once, replaced all the seals and bearings, and I would like to avoid doing it again. It does not take long with salad dressing instead of oil to destroy stuff. Whenever I get into anything deep I make sure to change the gear oil. It is actually pretty inexpensive by the 5 gallon pail at Tractor Supply or similar store.
That being said it has been in about 30+” of mud stew.
But the main reason I try to avoid it is that the Dana 60 stub shaft roller bearing isn’t sealed well. It is almost as poor as a felt washer, but it it rubber. I took a really good looking 60 out of a parted M1008 and the grease was 100% gone, the roller bearing was garbage, and the bearing surface on the outer stub shafts was destroyed. I’m not too familiar with the 10 bolt that is in the front of your M1009, but I’m guessing that it is also not fond of water.
Had to get new bearings, seals and outer shafts to the tune of $300+
Basically boils down to the fact I am too cheap to play in the water and mud.