This thread has been seen by quite a lot of people living in China so I'd like to update everyone since I just tried to enter the two main borders into Myanmar on foot with a visa (and failed).
Daluozhen is not open to foreigners at all. China border patrol will not even let you come close to the crossing.
Ruili / Mu-se is also not open to foreigners. China has no problem letting you cross the border to talk to the Myanmar border patrol but despite multiple attempts and phone calls, the Myanmar side will not let you enter the town - even for a few hours - even if we leave our passports, etc... we tried everything. We were told to "wait 6 months, maybe it will change..."
For what it's worth... we drove motorcycles from Xishuangbanna to Ruili and the scenery more than made up for the disappointment at the border so I still recommend trying! (and posting an update to this thread)