Years ago I had an SP1 with the pencil thin barrel. Loved that gun very much and had no problems hitting things with it. Like a fool I sold it.
Then I bought a Sporter Match HBAR. This has the full 'A2 treatment with the full Heavy barrel. A better gun all the way around, right.
Wrong! That damned heavy barrel is HEAVY.
It completely changed the characteristics of the gun. It is no longer easy to carry. And I don't see any additional benefits.
Like jomeokee said, find a couple at a store or gunshow and try them on for size.
I, personally, would opt for the lighter barrel this time.