if you don't have 400/500/600 lens then 3451 is more than enough for you.
Yes, I realize that, I plan to one day get a 70-200 L, so I know when I do that, the GT3541 will hold my gear. And if I ever step up to 400/500/600, I'll be ready too.
Now you have me debating on the Markins and PhotoClam ballheads!
I guess according the the ball and housing diameters, the PC-48NS is comparable to the Markins M20? Its $100 less than the Markins too.
Ball Diameter - 48mm/1.89in
Housing Diameter - 58mm/2.28in
Ball Diameter - 1.89 in (48 mm)
Housing Diameter - 2.28 in (58 mm)