Can't help feeling Oiltech is getting too much "unfair" bad press out of this. His waiting list for getting a casing altered is something like 12 weeks, so that gives an idea of the amount of casings he does. This is the only negative issue that has come to light, although I'm sure there are more, it is certainly a small percentage of the work he does.
I considered a modification on my new Avanti kit, but after adding the costs of all the parts I was fitting (£2500?) I decided against it and bought a new casing. I realise the quality of the metal/alloy used in the casing can be unknown and the quality of the modification will be dependant on the quality of the casing.
Never-the-less I am having a casing modified and will build it with mainly used parts, upgrading when I am confident in the engine. The upgrade would be dependant on not only the casing, but other factors as well.
Good luck to Oiltech and remember the hundreds/thousands of successful modifications.