The great thing about porters is that you only carry a daypack, a small water bottle, a jacket, toque, and camera gear. I did the trek to Everest basecamp from Lukla in about 10 days. I carried my Elan IIE, a Lowepro chest harness, my Canon 20mm 2.8, a Canon 28-70 2.8, and (gulp) my Canon 70-200 2.8. I kept polarizing filters on both longer lenses, and I carried 70 rolls of film, a few extra batteries. I had a tiny tripod, used occasionally. I often used my on-camera flash for catchlights/daytime fill. If I didn't have on-camera flash I would have brought my 550EX. I used a Lowepro allweather drybag backpack. Not once did my camera gear leave my side -- remember that when you are resting on a Thai beach after the trip.
If you are going digital, you will need a battery charger device and some kind of backup, like a portable hard drive/Wolverine, and lots of cards. Power is available most of the way, but you may have to pay a few rupees to use it.
The mix of chest harness and backpack served me well, and I was overall really happy with the trip. The long fast lens was heavy, but for my use it was worth it. Actually the biggest error I made was to bring hiking boots, which were rarely used and mostly were carried by the porters up and down (they wore flip-flops or runners). Were I to do it again, I might leave the 70-200 and take an extra flash.