Over the past 2-3 years, I've gone through close to 30 of these tubes. Mainly because I carry spares and don't need them myself but give them to others on the roadside. I use the 60mm presta valve tubes paired with 700x23 Specialized All-Condition Armadillo Elite tires and the last 10 times I've used tubes is because I got a new wheelset. I can't remember when my last flat was. I do always pump up to 125psi before I leave my apartment. There's no reason to spend $6-12 per tube for a name brand. Besides, Kenda is itself a brand name. I won't buy other tubes.
I've used both the Kenda and Michelin smooth presta valve tubes and the Kenda's are just as durable but a little lighter than the Michelins. If you're looking for a smooth valve tube this is a good choice although a little pricey.