Migration query - Oracle
I'm sure that such approach is feasible. Technically Grid 11.2.0.4 is fully compatible with RDBMS 11.2.0.3. You just need to be accurate in some parameters.
I believe that in a new 11.2.0.4 grid you won't use very specific "compatible.rdbms" or "compatible.asm" attributes' value ('11.2.0.4.0', e.g.) which might conflict with 11.2.0.3 database. Ideally you should use the same default '11.2.0.0.0' value in target GI.

You can clone databases from old to new GI, copy specific tablespaces if your schemas are compatible with transport_tablespaces approach. You can use logical dump created with datapump.
It might be very useful to use dbms_file_transfer package to copy datafiles (and dumpfiles created by datapump as well) directly from source ASM to target ASM diskgroups.

Good luck.