I own or have owned skis from all three of these companies, and I've skied the regular Husume. I'd suggest doing a search at TGR for reviews of all three - there's a long thread on the w99, a semi-long thread on the Bros 179, and a few posts on the Husume XTC. There's some reviews here on the w99, nothing I'm aware of on the other two. In general, the reviews on the w99 are more positive at TGR than here.
Based on the other skis I've used from these companies, I'd guess that the Prior will be the stiffest and most planted feeling, even with carbon, while the w99 will be the lightest feeling on the snow, nearly as stiff as the Prior, but by far the most playful and surfy (it has the most pronounced rocker in front). Priors and PM Gear Bros tend to ski closer to a traditional feeling, with mild rocker, less rise and splay. Have heard the new all carbon Bros are very lively; my Lhasas were already lively along the lines of a mid fat Fischer. OTOH, the 179 has an extra sheet of rubber, so that may act as a damper; have heard it's the smoothest of the PM's.
Hope this helps.