I've used NSI products for many years, my salon is exclusively NSI, I use Attraction, Secrets, Balance and Polish Pro. I love them all and have never had any major issues with anything. My clients are happy with how the products last and wear and so am I, so I have never thought to jump ship to any other brand because why try and fix something that isn't broken.
I think the key to any successful business/set of nails is to only ever use the system you have chosen, never mix brands.
It drives me nuts when techs complain that something is going wrong and seek help, we try and help only to find the tech is using NSI Attraction powder with Young Nails monomer, IBD primer, CND dehydrator and the list goes on.
For example, I know that NSI make and test all their products to work together as the system it is, so it's only logical when a tech tries to bring in a different brand of one product with that system, it is only going to cause problems.
Also, as with any brand, you should get training in that brand you have chosen and then be patient, it takes perfect practice to get the hang of a new system.