A new bugfix release of steem (0.20.6) is currently prepared for release next week. @reggaemuffin already merged the most important changes into his live test environment https://testbed.reggaemuffin.me/ (more infos.

I will do some tests regarding the changed RC costs:
The broadcasted operation can be seen https://steemd.com/@beembot

RC costs measurements

Version 0.20.5 was measured on https://api.steemit.com. 0.20.6 was measured on https://testbed.reggaemuffin.me/.

The RC costs were measured by:
For 0.20.6 (https://testbed.reggaemuffin.me/)

        node = "https://testbed.reggaemuffin.me/"
        stm = Steem(node=node, keys=[wif_posting])
        account = Account("beembot", steem_instance=stm)        
        rc_mana_old = account.get_rc_manabar()
        print(account.steem)
        # place for broadcast a operation      
        sleep(5)
        rc_mana_new = account.get_rc_manabar()
        rc_costs = rc_mana_old["current_mana"] - rc_mana_new["current_mana"]
        print("RC costs: %f G RC" % (rc_costs / 1e9))

For 0.20.5 (https://api.steemit.com):

        stm2 = Steem(node = "https://api.steemit.com", keys=[wif_posting])
        account = Account("beembot", steem_instance=stm2)
        rc_mana_old = account.get_rc_manabar()
        print(account.steem)
        # place for broadcast a operation      
        sleep(5)
        rc_mana_new = account.get_rc_manabar()
        rc_costs  = rc_mana_old["current_mana"] - rc_mana_new["current_mana"]
        print("Costs: %f G RC" % (rc_costs / 1e9))

Measurements

Transfer

version	RC costs [G RC]
0.20.6	0.300629
0.20.5	0.254544

Vote

version	RC costs [G RC]
0.20.6	0.115230
0.20.5	0.288244

Custom_json (follow)

version	RC costs [G RC]
0.20.6	0.404449
0.20.5	0.070962

Custom_json (reblog)

version	RC costs [G RC]
0.20.6	0.106790
0.20.5	0.092349

Comment

version	RC costs [G RC]
0.20.6	1.966627
0.20.5	1.821318

Conclusion

RC costs for a vote and a follow custom_json operation will be changing. RC costs for a vote are reduced by a factor of 2.5. RC costs for a follow custom_json OP are increased by a factor of 5.6. The RC costs of other custom_json operation is not affected.

The RC costs of all broadcasted operations are slightly increased, as now the execution time is now included in the RC cost calculation.