The Cisco 3750-X have also the gigabit based SFP slots as the ERS5632FD.
But you can only equip the 3750x with an etra module with 2 10Gig Uplink ports.
The ERS5632 has 8x internal 10gig ports.
Not very familar with the HP products, do HP have a stacking technology for their Access switches ?
Cheers