Hi windybum,
can't say about the '07 but I own or owned '08 58, '09 55 and '10 58.
Your '07 board should be from before the decision to make them longer at 250 cms. and lower the nose, but I guess main character must be similar to that of '08 58.
Those boards had a thick tail, very high apex rails and rather deep vee. From '09 on, nose was lowered again, rails got more tuck and vee was reduced; so newer boards rely more on the lower nose than on deep vee for stability, and gained much performances in the mean time. You should expect a much (much!) crisper ride and earlier planing and maybe need some more commitment during the jibe, not really tougher but less 'waveboard-like' if you know what I mean.
Probably the board would feel a bit smaller too, so better ask James in any case as for sail range. '09 55 is definitely a 5.9 - 6.3 board, althought it still carries a powered 6.6 extremely well; while '10 58 is rather a 6.3 - 6.6 board to me, and still carries a powered 7.0 extremely well.