In reply to ralphio: FWIW Dragons wouldn't be my first choice larger than a 4CU size 3 / Dragon size 4.
I replaced 4CUs with Dragons 1-4, but bearing in mind cost and especially weight, I bought DMM Demon cams in size 3.5 & 4 instead of Dragons 5/6. [Both were recently available at the stunning price of £32.50 from Rock+Run, unfortunately the price must have been too good, in that when I checked today the size 4 is now sold out, although size 3.5 is still in stock -
http://www.rockrun.com/products/DMM-Demon-Cam-Size-3.5.html ]
However, if I wanted maximum expansion range and I was less concerned about cost and weight I would also have considered a Metolius Supercam in medium or large.
Whatever you do with exact sizes of gear, sometime it will always seem the wrong decision, but in reality there isn't a massive difference between the two adjacent sizes in Dragons or any of the other cams.