Halogen cooking

I am thinking of buying one of these oven/cookers for use in the 'van. Does anyone have any thoughts or experiences on which make to buy or not?

The idea of using one to make gas supplies last longer was given to us by a couple we met in a car park off the A66 who were travelling in their motorhome. As we are in our first year of caravaning we are grateful for all the info passed on to us.