This is a difficult one, you will be limited by airline baggage limits - 20kg long haul and 12kg on the Kathmandu to Lukla flight. You can of course carry more as hand luggage but the real limits are how much you can physically carry whilst on trek and how many souvenirs you are thinking of buying along the way. There are lots of temptations!
On my two treks, the travel company Exodus placed no further limitations. All my heavy gear was carried by yaks so all I had to carry whilst walking was what I thought I would need along the trail during the day. If you are carrying all your gear you will obviously need to travel light.
Before my 1999 trip I trawled the net for information on trekking in the Khumbu in October-November so that I could decide how much gear to take with me. I remember reading somewhere that an Antarctic explorer , possibly David Hempleman-Adams made his trip with just one set of underwear. The writer compared this with a lady who took I think 40 odd sets on her trek to Nepal!
Anyway this is what I took with me :-
Clothing and Footwear
Medical
Other
What changes would I have made in hindsight ?
I think that I was well prepared, I had been with Exodus before and read up well before departure. I knew that at the end of a trek it is customary to tip in goods as well as cash, I planned to give away clothes, cards and dominos.
The Meindl boots were new and very comfortable. As well as on the trail, Iwore them on the colder evenings on trek. On warmer evenings I wore my sandals. They are leather with carbon impregnated cork insoles giving good support . They are adjustable front and rear allowing them to be worn bare footed, sometimes with thin socks and sometimes with thick socks depending on the temperature. Most other trekkers brought trainers instead but I was very happy with my choice, they were ideal for Kathmandu as well.
It is possible to wash clothes on trek, Namche has a launderette and there are plenty of washing opportunities along the trail. Be careful to avoid contaminating the local water supply though. It is quite normal to see trekkers with their washing drying on the top of their rucksacs. Most evenings in the Khumbu get very cold so you might not fancy washing your smalls in near freezing water and waking up to them stiff as a board in the morning. Lodges and restaurants have yak dung burning stoves in their communal rooms, most will be festooned with wet trekkers gear.
I only wore the down jacket above Namche, so I could have hired one from one of the many trekker's shops there. It would have been cheaper and the yaks would have had less to carry. You can hire most things from Namche, I had heard this before I went but didn't know whether there was enough gear available at peak season. I did buy a fleece sleeping bag liner for 750rp which was invaluable on the cold nights high in the mountains.
The best way of keeping warm in the mountains is to employ the layering principle, lots of thin layers are better than a single thick one.
Most other people in my group had brought snow gaiters. Fortunately these were not necessary. Had I travelled a fortnight earlier thigs would have been very different as there were tales of much more snow at Lobuche and above. If I go again I will pack a pair.
I decided not to take a pair of binoculars, I assumed that as I would be in a group someone else would have some, they did that was O.K. Next time I'll take mine to look at the details on the high mountains and to spot climbers.