The installation of VLS on those ships means something is alternatively gone. Adding UKSK on a Project 20380 type ship means you forgo either the Kashtan or the Redut VLS option. Likewise, if you put Redut VLS, you forgo Kashtan or UKSK. If you go with Kashtans, you forgo Redut or UKSK. In the case of the Buyan M, the 8 cells have to be divided between ASW, AAW and ASuW and that doesn't leave you much.
For a 2500 ton ship, two hangers are too much for a single hull, and the only way that is possible is with a trimaran design.
For an ASW ship, 8 to 16 cells of H/AJK-16 instead of U-VLS is fine. That lets you use Yu-8 ASROC, which has yet to be verified on U-VLS launches, meaning we have yet to see one launch from that.
A Kashtan type CIWS limits you to 4 missiles only, which are also command guided and literally works like MANPADs. The HQ-10 missiles are more sophisticated than that. HQ-10 missiles on such a setup, because the missiles are always exposed to the heat, which the HQ-10 launcher keeps the missiles enclosed, protected and cold. HQ-10 also operates on passive guidance, and a short distance from the back of the HQ-10 launcher, there are two radar receivers that takes and tracks the threat signals, which are analyzed by the EW system, then a copy is sent to the missiles so they could recognize and lock on to the threat. If the missile chooses to operate on IR mode, the radars would cue the launcher at the target, the cover would open, exposing the seekers, which is then cued by the radars to "stare" at the target to get a lock on. The Type 056 could be using combined radar sensor tracking (including gun EO) for that purpose. The Type 056 is said to operate with an advanced combat management system that integrates all sensors and weapons into a network. I would think the HQ-10 missile set up is more assuring than a Pantsir-M/Kashtan setup when it comes to supersonic missiles or saturated attacks under a high EW environment.
In a Norinco exhibit, their version of the Type 056 is enhanced further by adding two 730B CIWS while keeping the HQ-10.
There is a question whether VLS can be better than a slant missile launcher for close range air defense. The VLS fired SAM has to go up, then flip over with its TVC controls, and has to be guided by SARH if the missile is not an ARH. ARH for a small missile has an issue due to the space it takes for the power source and the radio emitter, which causes the missiles to be bigger. SARH requires illuminators on board, which limits you to the number of targets that are engaged simultaneously. If these are IR missiles fired from a VLS, they have to lock on after launch, they have to be command guided by radar through data link till they achieve direct lock on to the target. The beauty of the RAM type missile which the HQ-10 is copying, is that threat radar signal from the enemy antiship missile might be the strongest signal of all, being in the front aspect of the missile, rather than the heat signature at the missile's exhaust. Whether its passive or in heat seeking mode, the HQ-10 is lock before launch, compared to the lock after launch if using VLS, and for close quarters air defense, plus that the missile does not need to travel up then flip over, but heads straight to the target, cuts down on interception time. This is why I would prefer these missiles for close air defense.