P2 is a much better than a P1 amp in both: size and power.
It is much more comfortable to use it for a standing setup, because, it is not as bulky as P1. If you make a custom cable 2 xlr mono > 1 xlr stereo it works as a stereo amp flawlessly. And thats the only thing that is better on the P1.
Power of the amplification and the power consumption is way better than it's bigger brother. 9v batteries on the P1, can hold not more than 1/3 time of this AAA battery setup.. Its superb. Quality batteries hold up to 10gigs (±2hours of playing thru the night) for me. While the P1 is not as loud and powers up on a single battery only for ±3 gigs..
It has a good headroom (much more louder than a P1) for playing with a loud band and setting up a powerful headphone mix.
2 things, that could (and should) be improved:
1: Though the format is small, its not very VERY strong. I have had used it for 30-50 gigs already, always clipping it to my jeans strap, sometimes sitting on a chair, sometimes standing up, and, it's chassis has a dent around a XLR area, and a belt clip has a little lost its form.
This does not effect its performance in any way. Just it could be a little stronger.
2: The batteries, more than a few times, after a transportation have had fallen from their places, so almost 2/3 times, out of 4, after you arrive at a gig, you have to open it up and reattach the batteries in to their place.
Price - makes it a no brainer.
Would I recommend them? Why would you even ask it! Would recommend it by 150%. It is a must have for any gigging musician. Just to have it in their backpack with a cheap set of in ears (for example KZ ES4), if the venue is too noisy/loud/not enough monitors/not working monitors - you can save your day for a ±50eur and hear everything loud and clear.