The heap parameters displayed for the clhsdb 'universe' command needs to be improved for G1GC. The current output is as follows:
hsdb> universe
Heap Parameters:
garbage-first heap [0x0000000725200000, 0x00000007c0000000] region size 1024K

This seems inadequate. One suggestion would be to list the various active regions (along with the type (eden, survivor, old, humungous, pinned, etc) along with the top and bottom addresses. This could be done under a special option if the output is too lengthy.