It is common knowledge that you always should use a small piece of Velox rim tape (or other strong cotton rim tape) to cover the edges of the valve hole in the rim.
Plastic tape covered with cotton tape????? Why use the plastic? Do you need the extra weight of 15-20 grams per wheel? Don’t think so.. is it? Try the Veloplug to cover your valve holes (no extra tape needed after that). Look at: http://www.veloplug.com/
This tip saves you at least 30-35garms per wheel set in rotating mass!
I also have very good experience with the Veloplugs on the rims that have spoke holes drilled thru both sides (not like the Ksyrium and Eurus wheels). Veloplugs save more then 12grams on a 28-32 spoke rim and make tyre fitting more easy.
Plastic rim tape is out of the question I never use this. If rim tape then it is Velox cotton!
Back to topic.
Several Michelin A1 latex inner tubes I already ride for longer then a full year! They survive easily over the Veloflex Black Open Tubular or Michelin Pro2Race Clincher!
I do not experience much flats at all. Once in 6000km Is my average over the last 5 years (that is significant less then my training friends using butyl).
My oldest Latex Michelin inner tube in use is over 5 years old now! It is in my rear winter wheel that I ride on wet roads. I did repair this one 4 times (which is no problem at all) I simply use Simson Solution and Simson small patches of 15mm diameter (look at: http://www.simson.nu/producten.asp
). Never had the experience of a brittle latex inner tube, that fdegrove is writing about. Not even if it was in use for a longer period and lots of km/miles.
Michelin had one bad series of the Latex A1 inner tubes these are easy to recognize since these had blue valve stems.
I do ride over 15.000 km a year and only use latex inner tubes. Until half a year ago I only used Michelin and I never did experience one of the problems that are mentioned in this thread. I did try out the Challenge Latex over the last six month and I am very satisfied until now no flat at all! I like the Challenge because they are seamless an a bit lighter.
IMHO Michelin A1 latex is one of the best you can get.