Hey, I'm not trying to say you bought a bad saw. I'm glad you got a good deal on it and I'm sure it will serve you well for a long time.
As far as the MS361 compared to the 359.... I would say the power to weight difference and the company's designating one a pro saw and the other a farm/ranch. For me personally, I'd pay a little more for a Stihl over a Husky too, but that's just me. Also to be fair, the difference in price isn't quite as much as you said. I just bought my 361 and I shopped prices with my local dealers. The prices were pretty much the same. If I break it down to what I payed for just my saw, 18" bar and chain, it's $575. So that's $100 difference. Then with my other point of you now buying a non-CAT muffler (the 361 already comes with a non-Cat muff) you at $75 to $50 differance...
Again, I'm not trying to put you down at all. So I hope you don't take it that way. You asked the question, so I tried to answer. Glad you got a good saw and are happy with it. Have fun cutting and be safe.