Hi Prachi,
Yes, To see the actual performance benefits of HANA your SRM 7 system should be at EHP3.
However in the beginning of this post you have mentioned that you have already installed SAP HANA in landscape with deployed ECC and SRM systems. I guess that your SRM system is on lower (<EHP2) version of SAP SRM system.
If yes then I suspect you have installed it in your landscape because as per the released Master Guides, SAP has started support of HANA for SRM 7 as of EHP3.
Do you really have HANA working with SRM for lower EHPs of SRM? Don't you have any issues?
Regards,
Anil Bansal