I would like to know to what extent the Wave is “fraught with problems” – and what exactly are the “common” problems & “design faults” you refer to? Perhaps some other Wave owners would comment if they too have had similar issues, as one individual’s bad experience doesn’t provide an adequate basis for a general conclusion. I must say that these particular issues sound more like poor servicing rather than issues of durability and longevity. A valve & clutch adjustment after 6 months would seem pretty normal as the bike settles in. And if done badly, the noises will return rapidly. This would indicate poor service standards rather than poor manufacture. But if enough owners report similar problems then it may be that manufacture is indeed at fault, as stubuzz claims.
My experience (ie not generalisable either) is that Waves are quite a tough little machine. I have a 2006 Wave 125 (carb version) which has done 28,000 kms touring around Thailand, Laos and Cambodia and a lot of city work for past 3 years, with the odd 300 km mountain trip carrying about 180kg of rider, passenger & luggage. Never a problem, just routine tuning. I know of other Waves with more kms than mine and similarly no mechanical problems. Even when maintenance is neglected (a common practice here), the Waves still seem to go on forever.
My partner’s 2009 Mio (carb version) seems quite robust too. She bought new, and has only done 13,000 kms, but has had no major problems, with all routine services done on time. It has some quirks. Weather changes mean it is a bugger to start – maybe not an issue with the newer injected motors. I find the Mio more comfortable than the Wave for city work because of the lazy auto and larger seat. But the Mio is not as good as a Wave (or other semi-auto bike) in a hilly area. CVT belts don’t seem to transfer torque to the rear wheel as efficiently as cogs.
Never ridden a Spark, but would love to! It sounds like those extra 10cc offer a lot of fun. And the 135 motor has been around for a while, so should be fairly durable as well.