I think something missing here is that, generally, Insteon is at least on par if not beyond many of their competitors. There's nothing like the Keypads, for instance, and the dimmers are only matched in Z-Wave by Leviton (and even then not quite matched), which come in at the same price point. The newest Insteon dimmers are really second only to Lutron, for instance, and have been updated even over the last two years and are now thinner and even higher quality than the ones I put in when I first bought my house. It's not perfect, but if you want a bulletproof reliable system, they're still top notch and slowly but surely moving the bar forward.
Personally though, I have a primary Insteon system, but recognize that Z-Wave also provides unique devices that Insteon doesn't (and vis versa), so I have the Z-Wave module installed as well. Not really used yet, but the next big expansion is into Z-Wave with smart locks and enough outlets to support a decent network.