I'm happy with the 250 mile range on my CCM. Unless you're really off the beaten track that should be good enough and a couple of cheap cans will put another 100 miles on that if you really need it.

I've toured with mega tanks in the past that gave me a close to 800 mile range (40+ litres and riding slowly) and 1. full up they're so top heavy it makes riding anything other than tarmac difficult, and 2. you forget to buy more fuel, assuming there's loads in there. There's no point in having a big tank if you run it dry.

On the other hand a fuel range of 150 miles or less is a PIA. You're dependant on fuel stations turning up regularly - and being open. Riding at night, riding on Sundays, during "siesta" time, during a strike etc, are all difficult. In the past I've resorted to siphoning petrol from parked cars (and leaving money for it!) at night, camping outside garages waiting till they opened the next day and (in the dim and distant past) buying it in glass jars from a grocery store.

My 125 Suzuki has a fuel range of about 90 miles which, on a long trip, is almost unusable. You're forever trying to plan where you'll get your next fuel from. Miss a services on the motorway and you're dependant on the Lord to get you to the next one. I've had it cut out on the garage forecourt before now when I've run it down to zero.