Thorn Tree travel forum

what can you tell me about these travel agencies?

I need to know what you can tell me about three travel agencies that offer tours of Tibet.
One is online in the U.S. as China Travel Guide (chinatravelguide.com), and is Xian Marco Polo International Travel Service, in Xi'an.
The second is online in the U.S. as China Tibet Tour (tibettour.com.cn). It is located in Beijing, and claims to be connected with the China Tibet Information Center and the China Tibet Tourism Bureau. Elsewhere online it is identified as officially connected with the Ministry of Foreign Affairs of the PRC. I have been unable to confirm any of these claims.
The third is Access Tibet Tour (accesstibettour.net) in Lhasa. I have read in these pages commentary that they are very good to work with in planning a trip, but nothing else.
I would greatly appreciate learning about these companies before sending money to any of them. Thanks much.