Of note to solo trekkers: Interesting route - but I'll be blunt, the people whom I saw doing the route were vastly unprepared for the challenges of it. Sure, it is a trekking route, however, coming down from Cho La is extremely steep, and crossing the glacier at the end of the day is problematic. There were reports of people taking 10-12 hours to complete that portion of the trail. It is, in my opinion, a very dangerous thing to do on your own. Doing the other two passes is much easier - but be aware that if you are trekking on your own there are plenty of people up there while you are trekking, porters, etc. The problem is that they are on their own trip, and the porters that are bringing loads to other communities are more worried about getting home for the night, not helping someone who is hurt. You can be assured that help will come, but it will be in the form of either a horse or a helicopter - whatever they can muster. You will be laying there for many hours by yourself waiting.
I saw about 12 parties that were attempting it - several dropped out because they discovered that when they get to high altitude their bodies are fighting the altitude and most people got a cold, resulting in more rest days, and many dropped the whole idea altogether. Others were planning on doing the trek in record time, times that you will see here on this forum, which is just about impossible for most people and so they didn't attempt it when sitting in Dingboche sick with altitude. One group had their friend evacuated out via helicopter because of altitude sickness - did NOT take the rest days they were supposed to. One man went from Lukla to Namche in one day, then a rest day, then to Dingboce, then to Gorak Shep and felt great - then ended up on a 5000.00 helicopter ride out after getting altitude sickness up high.
Others attempted Renjo Pass after 25cms of snow, and found the other side a sheet of ice resulting in a sprained ankle and their friend took both packs the rest of the way. They were lucky...
This is NOT an 'easy' trek, and if you have no experience at altitude you are setting yourself up for either a pleasant surprise or a big disappointment. In my opinion, it's best to hire a guide until you know how you will do at altitude. Be very very very careful, and don't be afraid to take many extra rest days, go down, or just go with a friend. If you get HAPE or HACE and you are by yourself this is a life threatening condition and you will need people with you. Hoping that someone at your lodge will interrupt their plans at 7:00 pm at night to take you down is probably not going to happen, and they don't fly helicopters at that time.
Be careful, and if you are taking your own pack you need to take extra rest days or you will suffer at the very least. It's your life - I can see why 400 people go missing in Nepal every year trekking after the madness of Everest and the throng of independent trekkers who think that tromping at 5500 metres is a romp in the park. What you are all reading on these forums is the most romantic versions of the pass - believe me, it's hard and the amount of people who dropped out (wisely) was quite high. If it snows on those passes, you have a much more difficult day ahead of you, and you need to assess the avalanche danger accordingly, and be prepared with at least Yak Trax or crampons to make it. There are NO GUIDED TOURS up on the pass that go without Yak Trax, contrary to forum postings otherwise. Do some do it? I doubt it - the ones I talked to all use them, and my local Nepalese friends in Kathmandu say they all do too.
FYI - read up on altitude sickness. Again, I urge you that if you have no experience at altitude you need to hire a guide at least your first time. http://www.himalayanrescue.org
Good luck.

