With SSDs, it all comes down to firmware optimizations, and even though Adaptec has really done some catching up lately, the ML1231 is still the best choice for SSDs (even though it is old tech).
However, the only Areca to match/surpass the 5805's parity raid (5/6) performance is the 1680xi. Same IOP (1,2 Ghz Dualcore), and can be equipped with up to 4GB cache. Price/performance is strongly in favor of the 5805 here.
If you don't mind a 45s bootup, the Adaptec 2405 currently is the best choice if you want to run SSD Raid 0 with up to 4 drives and are on a strict budget.

