I am not sure about the JetA1 engines. My AA5B would now be costing me about £60 per hour in Avgas, so building the MCR was partly a way of ensuring I can fly long term for less money. The MCR burns about £15 per hour, and the Rotax 912 has the best reliability of any engine in the PFA fleet.
The JetA1 solution will reduce the cost by another £8 per hour but what about reliability? I think it will be at least 7 or 8 years before any of the experimental engines are truly proven in the field. You also have to look at the cost of engine purchase. I got my engine (912ULS) 18 months ago at an all in cost of £8600 inc vat and carriage. At the time the Wiltch (forgive the spelling) was available at £13,600 all in, a difference of £5000!
The MCR-01 ULM has carbon fibre wing skins, as does the MCR-04.
Rod1