Ak-Sai travel was also working together with ITMC on the southern Engilchek base camp. Ak-Sai have a good reputation. Both organizations was a mixed Russian-Kyrgyz companies, but they are both mananed by Kyrgyz director.
Moreover, the Kyrgzyz side of Khan Tengri is rather easier in ascend and administrative task also (no visa for 2013, only border permit for 20 $), despite the actual danger below the chapaev peak in the Pogrebetskiy Route on the Semenovskiy Glacier. There is much to say about it, and it represent in some way similar danger than the norh face regular Kazakh route. The north regular Kazakh is below the Petka peak, 6121 m known as the west shoulder of Khan Tengri, is a rather difficult and tireless ascent, below possible giant corniches. You have to reach 6121 before descending to the pass 5800 where trying to establish camp 3 on the windy pass. And after trying to submit Khan Tengri next day (or in two day, on camp 4 at 6400).
On the Pogrebetskiy route you were exposed to avalanche from the east face of Chapaev on the sector so-called "the bottle", it's on the way from camp 1 (4200) to camp 2 (5200), after it's an easy climb to camp 3, wich is very near the north Kazakh route camp 3 (only 200 m) but here it's just 100 m below the pass on a serac sector very well protected from the wind. It's a very confortable camp to stay and wait for a suitable meteo window. Nice place with full of sun and an inredible view to upper south engilchek basin.
The so-called "bottle" area on the way from camp 1 to camp 2, have suffer some human disaster, but most of it could be avoided by simple security advise : do not start to early from the camp 1, be under the danger at the firt day light (5 am) not to early, not to late. Area range from 4350 to 4700, it is not a very altitude. And be out of this sector last 9 am not more. It means that you need a good acclimatation before climbing. It's the pass to the success. I recommend you to make for 4 days the Engilchek trekking on the giant Glacier from Maida-Ady (or At-Jailoo) to the southern base camp at the junction of Svezdochka and Engilchek glacier (just in front of the north wall of Pobeda 7439 !). I've made in solo on 2010 before trying to summit Khan Tengri. I was in perfect condition for Pogrebetskiy route, each day reaching a higher camp, wich is reduced the risk. But too much snow defends the access to Khan Tengri. Nevertheless it's a great adventure in an incredible mountains, not less than Himalaya !