Nice review! My two cents:
For the All-Star if you find it slipping I recommend getting another set of pads and mixing two sizes. I'm a 7-3/8 and in theory the large should fit me, but the large slips, but the medium is too tight. M/L mixture is PERFECT for me. As for the looks, no, it doesn't look great, but I think the padding is the best of any other option, so I'll take (perceived anyway) improved protection and comfort (again, my perception) over looks.
I don't notice the weight or have venting problems with the UmpLife harness (I did have them with the DeltaFlex, because that harness is designed for catchers, so when you wear the mask forwards the DF covers the vent holes - that's not an issue with the UL, but overall I do like the DF harness better because I think it slips less.) I'm pretty certain the shell of the AS is the same size no matter what padding you get. Mentioning that only because this issue was mentioned on the Rawlings.
I'd REALLY love if Gerry Davis and/or @MadMax come out with a true UMPIRE skull cap - with great padding made for umps, but until I can consider that option I'm sticking with the All-Star and recommending it to all my partners. Overall what I love to see, no matter which one, is so many of us using skull caps now!