I decided to replace my calor with 5kg BP last year to reduce weight, no probs and, yes, most importantly noticeably less nose weight.
Issues with BP: the gas is propane and the convenient 5kg bottles are smaller than Calor propane therefore run out more quickly. And unfortunately BP gas distributors are few and far between - see the BP website http://www.bp.com/sectiongenericarticle.do?categoryId=9007797&contentId=7015926 and note that the 5kg bottles tend only to be available at caravan dealers and the like (mostly Truma stockists), very odd - look at BP's map.
Alan