Well I just got my VPX Cartomator, P+350 and SS TTip from HV and I have to say that this setup is awesome. However, i find that tip gets pretty hot really quickly and the flavor is a bit muted (which i expected). This setup i will likely use while driving. I guess one benefit of the warm tip is that it will be good in these cold winter months.
I have the P+650, VapeMate and SS Whistle Tip which I love as well. However, as it gets so dark so quickly I found that I was wasting too much juice as I was squeezing too much while driving. The flavour is as good as dripping and the VapeMate seemed to create a barrier for the heat to the drip tip. This combo I will likely use when I don't have to be out and about and the battery life is phenomenal!
Finally, the P+10 which has been stored most of the time will be my preferred mod used at parties or events. I picked up some XL Dual Coil 1.5 cartos which should be sufficient but man is the length huge. My better half has the P+650 and P+10 and she prefers the P+10 due to its form factor. In comparison to myself she rarely uses her P+650 at the moment. She brings extra batteries while at work when using the P+10. She has said that she will likely use her P+650 when she isn't concerned about holding a large mod.
Enough of my rant/summary but I kind of like watching the air bubble grow in the tank which can't be done with a SS tube. I guess if the tank doesn't crack I'll be in vaping heaven with my setup. So if David comes up with a custom tank that maintains the lines of the P+ while having a method to see how much juice is remaining I'm certain I'll be picking up some of those as well.
My VPX Cartomator is a brushed finished which was supposed to be the same finish as the P+ but it isn't. I would recommend if you are looking to have a tank that is as close as to the same finish is to simply purchase a satin tank from VPX reseller. The pic from Cry above shows how similar the finish is.