A thicker foil does have a wider tolerance with respect to varying angles of attack. (a thicker leading edge will be less critical to changes in AoA) so like I said earlier a thicker foil will initially give beter results and feel less prone to spin out(and recover more easily) but like many things in life its at a cost somewhere else. Might well be you are actually a bit slower with your new fin and other sailors might find the drakes spin out less when fully maxed ??? It all depends on the sailors ability;conditions and what they want to achieve. V max. Vmg.playful feeling.. control ???
Very often a fin that has to be coaxed initially (ie bear away; accelerate and gradually increase load) will give higher Vmax but not everybody wants to sail like that and in some situations you simply cant..
Thats why its very difficult to give broad assumptive answers.. We all give answers based on our own circumstances and limitations..
Basically (IMO) if you want to go really fast fit smallest thinnest fin you can just cope with at slow speed; coaxing into life slowly... When its up and running it will be great. (Highest Vmax)
If you want to simply go and arent concerned about Vmax fit largest fattest fin that you can cope with at highest speed you are likely to achieve.(Highest VMG)
Somewhere between the two is freeriding. (and wave sailing ???)