Of course subjective but currently on ART999 with a cut down 420 tail. Competent (+) rider. Mostly prone surf but sup and wingding in waves. 350 or 375 progressive? ART 899 on way....
Thank you......all you foil nuts! 
I use 375P on my ART999. Much improved over the 370 I used originally.
Recently tried it - 375P - on my BSC1060 for a light wind day and it sped -up and loosened up that foil well.
I am 78kg and primarily winging.
Many thanks jrc. I floated this on the axis Facebook group as well and the 375 was also the most suggested.
I enjoyed the 380 speed tail with a -1. Very loose and fast, easy to cut winglets off to loosen it up further.
I wouldn't get a 380 though. get a new progressive 
370P is a good choice for sure, I would say try with the shim, it gives more control and better stall speed.
I also have the 325P, it is really good with 899 and 999.
Been using 350p with 899 and 1099 .. noticeable improvement from 400p on both 99's at my weight (68kg).. winging, prone and dock.. looser, faster and less tendency to stall .. highly recommend 350p
agreed on 325P. If I could get a 300P I think that would be great. The X99 series just seems to come alive with smaller tails. They feel like a dog (in comparison) with the wrong tail.
See that your asking for "all around", I would chose the 400P if you are above 180pds. Below that the 350P would serve you well. Anything smaller will tune towards performance and away from Stability.
I'm 64kg, prefer the 350 to the 375 for 899 and 999. Pretty sure a 325P is inevitable after reading posts like this!
