That has been a point of discussion between myself and Bltizo in the recent past. The first two Sovs have the rear pair of AK-630s very close to the helipad such that a taller CIWS with a radar and E/O turret (such as an 1130) mounted at those locations would endanger any helicopter trying to land on the pad. This is why I think they will either mount a single 1130 in the midline of the ship at the rear, or they will keep the 630s as they are. Or alternatively mount the 1130s further away from the helipad. The newer 956EM variant has the Kashtan CIWS mounts much further away from the helipad and so the PLAN could easily just swap them out for 1130s; it remains to be seen if the 956EM versions will have an HHQ-10 launcher. If they do that would represent effectively three CIWS-type weapons in an 8,000 ton ship, a setup even the 055 doesn't have the luxury of receiving.
The Type 055 will have better AAW.
They have 128 cells and can afford a very effective quad packing of ESSM type short to mid range missiles to compliment the HHQ launcher and the 1130.
...and still have plenty of cells for good long range AAW coverage, good ASW ASROC type coverage, and plenty left over for good ASM coverage as well.
A Sov with two gun CIWS and an HHQ would be adequately covered, particularly since they only have 32 cells for AAW coverage after that. With eight canister ASMs and eight VLS ASMs they will also have a very strong anti-surface capability.
IMHO, the Chinese upgrade is going to make the Sovs a more effective, and longer viable ship for them.