Lordy, there seem to be as many breather solutions to A10s and A7s as there are bikes! In my opinion (!), the stock setup is the best. It's not perfect but, with everything else in good condition (and I mean GOOD condition), you'll have the best situation obtainable under circumstances that we have. In truth, I don't know what the BUNN system is and if anyone has experience with it, please report.
The Bunn Kit was developed by one of our members , Rex Bunn. He was searching for somthing better for his B44 and ended up designing a whole new system. They do work really well & Rex keeps owners updated as developements continue. He is currently working with HD & RE and they both may end up fitting them as standard. I know that RE fit them as factory approved accessories. He has just finished reworking the ones fitted to the Bullet Electras & will have the modified ones out soon. Not the biggest seller but can definately dry up those weeping cases.