If you do it right the extra wear on the chain/sprockets and clutch is minimal. The system really takes a beating when you're learning, however!
It has the power it needs, right where it's needed. And I agree with you about durability, mines at over 70k and still kicking, rusted to high hell but reliable. Requires a smack to start sometimes, that's itI haven't had any problems with mine due to design flaws; it was all due to having lived outside before I owned it or simply being neglected. It is possible these motors are susceptible to failure when neglected, however. I just really haven't seen any mechanical failure on here due to flaws in the design. It's possible there have been some, but it certainly isn't common.
It is also funny how they're speaking in general about these motors with 30,000 or 40,000 miles on them. Finding small bikes like these with 20,000 or more miles is rare, so I don't know how they're able to make such generalizations.
Calling an SOHC 400cc parallel twin gutless is silly; they're obviously biased for whatever reason. Of course it isn't powerful, but it is competitive in its own category.