How long is a good lenght of time, and how often are you going through
batteries? They typically need to be replaced every 2 to 3 months, depending on use. Really, I've never seen one so flimsily built that even heavy puffing would tear them apart. Especially the batteries. I suspect there are other problems.
But, yes, the m401 is a good choice. A bit hard to find at the moment, everyone's out of stock right now, but should be restocking soon. You could order direct from China, but they're probably backed up too, trying to restock everyone. Watch Puresmoker or LitecigUSA. Or consider a 901. Very reliable and a good choice for a beginner. Many places still have those on stock.