Simple answer is, they will. What most of these newer style 'expensive fins' have is greater control (upwind/downwind) and much larger wind ranges - we're basically near the point where you can have one fin working well in all conditions from 10-30 knots. For just recreational sailing I wouldn't bother with any of these larger cut-down fins, just stick to a 70 or even 68cm.
The only downside to these types of fins is they are usually VERY fragile. The trailing edges on them are very sharp and can chip if you aren't careful with the on the beach (not to mention you can cut your feet on them if you aren't careful with them on the water). Other than that though, the performance is really another level beyond any older fin and you will probably enjoy the sailing more having one under your feet ;-)
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