hi
we do have around 3 6500 boxes running SSO with 12.2(18)SXD5 without any problems til now.
But we didnt upgrade that from RPR+ and it was running for around 8 to 9 months with SSO only.
we havent faced any kinda probs with our 7600 boxes too with Sup cards in it with the same ios code and SSO for reduandancy.
regds