Having had a number of conversations with caravan dealers, site managers and caravanners, everyone I have spoken to is in agreement that if you are so heavy with your noseweight you cannot carry your gas bottles in the gas locker then the weight saving by changing to a so called light weight gas bottle is not going to be great enough to make your noseweight ideal. You would be better off saving the extra money for the refil and carrying your gas bottles inside the caravan.
Having lifted the "light" and "heavy" bottles, the weight difference is noticeable, but not significant and certainly not going to be enough to transform an unstable outfit into a stable one.
In fact most of the people I have spoken to have felt the calor light bottles are a rip off. Just an excuse to charge an extra few quid for a refil. For what it's worth I have also been told that they have abandoned the gauges on the calor light bottles too as they did not work.
One thing to be aware of is the BP gas light bottles are a bit tubby , and the 10kg is quite tall, so it would be wise to check they fit in your locker before buying . I like being able to see the gas in the bottle , tis very handy .
I have two 6 kg calor light bottles in my front locker and the saving in weight compared to the 2 old type 6kg bottles is app 9 kg's,not insgnificant as far as I am concerned.
Saxo1
Don't forget that it's only the bottle that is lighter, not the gas! My understanding is that a standard 6kg calor gas bottle weighs 15kg full and 9kg empty, and the new light bottles are 10.5kg and 4.5kg. Therefore whilst Calor advertises it as being approx 50% lighter, when comparing two full bottles, it it only 30% lighter. IMO it is not worth the extra money for the weight saving, however I do like to know when I am running short on gas so I have one of each bottle. I use the heavy one for day to day use (cheap gas) and the light one as a back-up (expensive gas). It is also my understanding that the gas-trac indicator will only move off the full mark when the bottle is half-empty.