What exactly do you mean by capability based addressing Vs capability object model? Is it the use of capabilities to grant access to particular chunks of memory? What do you see as the pros and cons?
Paper: https://www.cl.cam.ac.uk/research/security/ctsrd/pdfs/201406...
"Motivated by contemporary security challenges, we reevaluate and refine capability-based addressing for the RISC era. We present CHERI, a hybrid capability model that extends the 64-bit MIPS ISA with byte-granularity memory protection."
Capability-based addressing https://en.wikipedia.org/wiki/Capability-based_addressing is hardware that implements 'fat pointers' that point to ranges of memory so its not possible for a program to address memory it shouldn't. Basically, it forces programs to be 'memory safe' https://en.wikipedia.org/wiki/Memory_safety even if written in memory-unsafe languages such as C.
http://www.cs.washington.edu/homes/levy/capabook/index.html
The surviving, capability architecture is System/38 -> AS/400 -> IBM i. A side effect of better architecture is that they are also incredibly reliable. One person here described them as the tanks of their company's servers.