Am I the only one who doesn’t love Harbeth P3esr?

The P3s like every other Harbeth speaker develop more bass and a smoother high end as they accumulate hours.
As for the KEF LS50 comparison I owned them and could never get rid of the metallic sound quality although it did minimize. They definitely have more bass than the P3s but are significantly less transparent in the midrange.
The P3s have excellent bass with the right amplifier- don’t be afraid to give them plenty of power- and once run in have detailed and natural sounding treble.  
The midrange is the star though and at times can be startlingly real.  

A small sealed sub like an SVS SB1000 or SB2000 will make the bass a non-issue, assuming that they are in a relatively small room. I'm using the older SVS SB12 NSD with mine.

I've always found the P3-ESRs a little smooth (hardly bright).  However, everyone's taste is different.  If you've been living with a smooth, maybe recessed-sounding speaker for many years then, yes, I guess the could sound bright.  Give them several months to "run in" and, more importantly, your ears to "run-in" to them and you might feel differently.

Common mistake buying equipment based on reviews or audience it at dealers. Now you will have to adjust your ears to them and I’m not recommending listening other equipment nowhere else because when you come back you will hate them more or sell them who love their sound. Honestly I hate their sound too so you are not only one 

since they are close monitors they need to be used closer than 2.5mt. they also need to be placed very close to the back wall. not far more than 50cm. as a matter of fact they’re more like desktop speakers than bookshelf. falcon’s are a little bit forgiving on listening distance but more or less all ls3/5’s are need to be used inside 2.5mt. distance including original rogers. I listened them all (spendor, graham, rogers, harbeth, falcon) except shun mook. falcon sounds a little bit exotic but harbeth is the best among them. additionally finish is playing an important role on sound signature. I like the rosewood’s sound.
a good low powered English amplifier might help too or a Japanese el84 tube amplifier is even better.