Despite the fact that excellent shots with high IQ are taken regularly with crop and 4/3 cameras, I think it's not disputable that FF can produce superior results, both in terms of noise at high ISO and the ability to crop more extensively without degradation among other things. The question is: are you willing to pay the price in weight and $ for that advantage. Professional photographers are, hence the predominance of FF in fine portraiture, wedding photography, fine publications, sports and photojournalism to name a few. If there were no advantage, do you think they would pay the 2x cost? In photographic equipment, like many other things, the relationship between cost and performance is not linear - you may have to pay 2-3x the cost for a 10% improvement in performance, and only you can decide wherther that is important enough to you to justify the price. Sometimes size/weight/price does matter, and this is one of those times. For examples, all other things being equal, larger telescopes outperform smaller telescopes, and bigger loudspeakers outperform smaller ones, and medium format outperforms 35mm, just as a full size sensor can outperform a crop sensor if they're both of the same technology and vintage. It's up to you to decide where you want to be on the price/size/weight vs price continuum (there is no free lunch, everything is a compromise)