the defy3 is a fine bike and by no means is holding you back, no climbs or rides will be any easier on the defy advanced, as people said it may make things worse due to smaller gearing range and the wheel may not last as long.
My suggestion is do what I did when I bought my bike and was 292lbs... set a goal to reward myself with whatever bike I wanted when I crossed the 200lbs mark... safest bet ever, I'm still @24X