The GP 2 takes about 24 seconds longer to boil 500ml of water using the Petrel G3 than the SOTO Micro Regulator. They're roughly the same size. I measured the lengths of the GP2 to be 77mm (folded) x 88mm (extended). The SOTO is 80.5mm (folded) x 88mm (extended). FireMaple quotes the folded length of the GP 2 to be 72mm. I don't know how they got that measurement. They either did not include the micro windscreen or the bit that screws into the gas bottle with the O-ring. The height for the Petrel when mounted to the GP 2 measured 268mm to the lip (i.e. not including the lid). I modified the channels at the base of the Petrel to accommodate the SOTO which resulted in the Petrel's lip height of 263mm. Although their dimensions are very close, the flame of the SOTO is closer to the base of the Petrel due to the domed/convex design of its head. I chose the SOTO MR over the Windmaster because its head design produced a broader flame compared to the Windmaster's more concentrated flame. Plus I wanted integrated pot stands and not a separate piece.
The GP 2 feels like a quality burner but it is a smidge behind the SOTO in every department but there's not much in it. The flame control of the SOTO is a tad better and it is more powerful which accounts for the faster boil times along with the flame sitting closer to the base.
The GP 2 is a tad heavier than the SOTO with my example weighing in at 95.6g compared to the SOTO at 70.9g. That's approx 25grams heavier, but the GP 2 has a lighter pouch so it claws back some of the deficit if one was to use their respective pouches to store the burners within the Petrel. However, this does not apply to me as I use a hanky as it provides better protection to the burner as well as to the inside of the pot. And it can do double duty as a rag to dry the pot or whatever. The whole kit (G3 Petrel w/lid + Jetboil cannister stand + 1/2 full fuel cannister + stove + hanky) came to 466.7grams for the FM GP 2 compared to 442 grams for the SOTO MR.
There are only 2 areas where in my opinion the GP 2 is better than the SOTO. The first being the pot supports. The GP 2's arms are easier to deploy and extend out further providing better support for larger pots and pans. The tiny swivelling "winglets" also accommodates smaller pots better than the SOTO.
The 2nd area the GP 2 beats the SOTO is value for money. IMHO, the GP2 is about 90% the performance of the SOTO at about 40% of the cost. Saying that, I still prefer the SOTO because of it's 1) convex flame profile (the Petrel's heat exchanger acts like a windscreen in my experience); 2) lighter weight; 3) better regulator (more precise flame control for simmering); 4) more powerful ; and 5) great reputation of its Piezo ignition system. YMMV.