As you said 'cost' compounded by the fact I got a good deal on the SM version second hand, to buy then kit out a Carf A4 must be well over 15k

It's not that much work considering we used to have to build from boxes of wood, anyway I'm going to see how heavy the stock build is first. Ali reckons the model is to small to warrant the extra weight so I probably have a rethink. I'll just wait and see what the kits like I suppose.