There seem to be at least two quite distinct cases in the amateur(ish)/GA sphere being discussed here, and arguments against one seem to be used to decry the other. I think that is false logic, verging on sophistry.
One case, which I supported in an earlier posting, is an engineered, tested, monitored, development in one country (e.g. Sweden for the Volvo-re-engined Pawnee with large, low-geared prop), acceptable to the regulatory authorities of that country which is not a third-world certificate-of-convenience situation. Other European (and wider) countries CAA's, e.g. UK CAA, should make it easier to duplicate that work instead of applying the full rigour of an all-new certification regime - they know the latter is unaffordable, they know the other country (Sweden) is a reputable authority, and they are being awkward for the sake of it. "Jobsworth" mentality. If Genghis and others really cannot see any case for this, then OK we just have a plain disagreement and that's that. The CAA happens to agree with Genghis. Hard luck on those like me who want to save cost and improve the environment, with no more risk than launching a Comet or a Concorde on the world. Which has killed most, by the way, the careful amateurs with regulatory monitoring, or the fully certificated commercial jobs which happened to have fatal flaws?
A quite separate case is the "right" claimed by some individuals to try whatever they like as long as it is "only them that is at risk". Arguments for and against this should not cloud the issue of the first case. Personally I find it fairly evenly balanced. I suppose I wish there were a "safe for third parties" route whereby these candidates for the Darwin Club could have a go. Occasionally another Wright, Whittle, Cockcroft etc. would emerge - Oh, they did in fact! - and the rest would lie between the extremes of the birdmen-off-the-pier embarrassment and the fatality of the guy who embedded himself and his rocket-powered Chevrolet(?) in the cliff-face.
By the way, the latter fruitcases do it anyway, rules or no rules, so why the argument?