i was trained and specialise in fusion pre-bonded extensions, however i have applied micro-ring extensions to my friends and my sister's hair in the past (as the micro-ring method is simalar if not easier than fusion pre-bonded).
Anyway, my friends and sister found that the micro-ring extensions didn't tend to last aslong as the pre-bonded extensions and that they fell out quite easierly (when brushing). Obviously, you need to ensure the rings are tighten enough to prevent them coming loose and falling out and you also have to be very careful when brushing your hair with microrings or any extensions for that matter and be careful not to get serum/oils near the bonds/rings as this could make them slide out... but as mentioned, my friends who have pre-bonded fusion extensions all the time and then tried micro-rings a few times, have now gone back to pre-bonded extensions as they just found them easier to look after and weren't alway worried about them coming out easy.
Having said that, i don't think micro-ring extensions are any less safer or better for the natural hair in comparasion to any method of hair extensions...
All hair extension systems have there pro's and con's and some methods are suitable for one hair type and not another and visa versa...
Aslong as the extensions are applied correctly by a qualifed and experienced hair extensionist, and that you follow all aftercare advise, use correct aftercare products, have regular maintanance appointments and get them removed professionally, i think you should have no problems with any method of hair extensions damaging your natural hair...
its the untrained and unqualifed people who apply extensions and use incorrect application techniques, incorrect removal processes and the lack of aftercare advise given which gives hair extensions a bad name... not to mention the clients who don't follow the aftercare advice and pick and pull the extensions and the bonds ect... which in turn can damage the natural hair!
You should just have the method of hair extensions which best suits your lifestye and hair type/conditiion and a qualifed extensionist can recommend the best system for your requirements.
HTH. If you have any other questions etc, PM me and i'll gladly help the best i can.
Laura X