Sab S430 gullwing stab

I can get a bargain on a Sab S430 gullwing stab. My foils are Balz 899 (most used) 799 (favourite when wind is constant enough) and 999 which I use in low or very irregular wind, I like the torque of the big wing but obviously it is slower than the smaller ones and the one I use the least. I use the 93 cm fuselage and 93 mast.

so far I only used a S399 stab which looks small to me and felt quite unstable in pitch initially but am coming more & more to grips with it. I run 1 deg shim which improved pitch stability, but may try to reduce that to gain some more speed on the smaller wings.

for the 999 I feel this stab is either too small or I need to shim it more than 1 deg because even when moving the foil mast 2 cm fwd it remains very back footed.

Does anyone have experience with either of these stabs? What can I expect from changing from S399 to S430? Sab does sell some glider sets where the balz wings are paired with the S430 stab so does not seem like I can go wrong, but would there be actual benefits?

I have no issues with roll and yaw stability on the S399 but it is quite sensitive in pitch so I have to be really on top of it. Could the S430 gullwing be more relaxed?

I'd shim it until you notice it becoming front footed at speed. Then back off a little or run it there if comfortable.

430 is a less lifty less locked in version of the 450 but way more locked in than the 399. The best riders love the looseness of the 399, I prefer a locked in less skaty feel so am 450 all the way. I do add 1.5 deg shim to my 999 relative to my other 899 799 with same stab (450)

Interestingly on my geezer downwind set up I run the w1110 with 399, good combo. I was running the leviathan 950 with s380 (a smaller version of 430) and the thing wouldn't turn, so I dropped down to 370 and it really loosened up the pig levi 950.

I bet you can balance things with what own. Why not try moving your mast and sail further to balance things, 20mm of foil movement is not that much.
I use the 999 and the 799. They have a about a 55mm difference in cord length. I find I need to move the foil mast by at least that distance to maintain the same pitch balance.
My foil package came with the 430 back when the brand was still Mosses. I think it is a very user-friendly stab and that's consistent with where the market was at that point trying to help people learn and not scare them off. The gull wings help simmer yaw and help resist sail side loads when you are too flat in roll. It is big in span and area, so it has a calming effect in general. The big con for me is that the wing tips turn up so they are closer to water's surface, and I would often breach the wing tips of the stab mid gybe particularly in short chop. I switched to the 483 stab that is flatter and has down turning tips, it's been working well. Its faster and it doesn't breach the tips; it took a minute to tame yaw and learn to sail with more windward heel when the sail is loaded. I have not used the 430 since and I am considering downsizing my choice in stab.