The difference is not between senior and junior level HR but the response to your proposal would depend on the organisation's culture, individual ability to understand the ROI etc. Many HRs (but not all) do not understand business issues. I have seen many senior HRs also talking like immature person.
If you wish to engage HRs, then use jargon as much as you can. Use hi-fi concepts though these could be irrelevant to the client's organisation. Many HRs are disempowered and they wish to fantasise with the fancy HR concepts. Take them to the dreamworld and see how your business grows.
In the training field, I have seen companies have grown exponentially though they never talked about ROI on training. You may use this formula.
20th January 2017 From India, Bangalore