When I was selling firewood my favorite combo was/is a nice 50cc saw and a nice 70cc saw, that's about the perfect setup IMHO. The Makita/Dolmar 6400/6401 is 64cc, but pulls like a 70 and they often can be had used for a fair price at you're local Home Depot too rental shop. The good thing about this saw is the fact you can upgrade them to 79cc or to an aftermarket big bore kit. You could also just find a nice used Dolmar 7900, but people seen to hold on to them pretty tight. If you go new then you have many options and all of them are pretty much awesome.
So to answer you're question. YES!! get a larger saw, you'll wonder why you ever did without.
Now how about some eye candy.7900
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390xp
576AT and 441CM