Hello,
Just because a business (or any other type of borrower) ends up in NAMA does not make them a problem borrower. They can be performing perfectly to their contacted terms, but may soon be moved to NAMA because they were a former customer of either Anglo or Irish Nationwide (subsequently merged and renamed the IBRC, which is now in liquidation).
My personal view is don't worry about it in terms of business reputation or immediate impact on how your current bank loans are structured as there is zero impact as long as you are paying your loan to terms etc.
However when opportunity permits, I would strongly urge you to seek a refinancing opportunity & move to one of the Banks remaining open for business (preferably a business bank) as you will need various other facilities in the future - be it overdrafts, FX, asset finance, additional loans etc.
If you are not familiar with how to go about this, speak to your accountant or a decent financial advisor, there are plenty of people with experience in helping good borrowers move to new banking partners (and also a few banks actually interested in gaining quality new clients).