ro.ril.hsxpa = indicates hsxpa support of target network :
Code:
ro.ril.hsxpa=0 - UMTS r99
ro.ril.hsxpa=1 - HSDPA
ro.ril.hsxpa=2 - HSDPA/HSUPA
ro.ril.gprsclass = inidcates GPRS class of target network :
Code:
Class 2 : 3 slots : 8 - 12 kbps upload / 16 - 24 kbps download
Class 4 : 4 slots : 8 - 12 kbps upload / 24 - 36 kbps download
Class 6 : 4 slots : 24 - 36 kbps upload / 24 - 36 kbps download
Class 8 : 5 slots : 8 - 12 kbps upload / 32 - 40 kbps download
Class 10 : 5 slots : 16 - 24 kbps upload / 32 - 48 kbps download
Class 12 : 5 slots : 32 - 48 kbps upload / 32 - 48 kbps download
More info Here 

ro.ril.hsdpa.category =
Code:
Cat 1 = 1.2 Mbit/s
Cat 2 = 1.2 Mbit/s
Cat 3 = 1.8 Mbit/s
Cat 4 = 1.8 Mbit/s
Cat 5 = 3.6 Mbit/s
Cat 6 = 3.6 Mbit/s
Cat 7 = 7.2 Mbit/s
Cat 8 = 7.2 Mbit/s
Cat 9 = 10.1 Mbit/s
Cat 10 = 14.0 Mbit/s
Cat 11 = 0.9 Mbit/s
Cat 12 = 1.8 Mbit/s
Cat 13 = 17.6 Mbit/s
Cat 14 = 21.1 Mbit/s
Cat 15 = 23.4 Mbit/s
Cat 16 = 27.9 Mbit/s
Cat 19 = 35.3 Mbit/s
Cat 20 = 42.2 Mbit/s
Cat 21 = 23.4 Mbit/s
Cat 22 = 27.9 Mbit/s
Cat 23 = 35.3 Mbit/s
Cat 24 = 42.2 Mbit/s
Cat 25 = 46.8 Mbit/s
Cat 26 = 55.9 Mbit/s
Cat 27 = 70.6 Mbit/s
Cat 28 = 84.4 Mbit/s
ro.ril.hsupa.category =
Code:
Cat 1 = 0.73 Mbit/s
Cat 2 = 1.46 Mbit/s
Cat 3 = 1.46 Mbit/s
Cat 4 = 2.93 Mbit/s
Cat 5 = 2.00 Mbit/s
Cat 6 = 5.76 Mbit/s
Cat 7 = 11.5 Mbit/s
Not speed related, but still nice to have :

ro.ril.enable.3g.prefix : adds the 3G prefix to the operator name.

ro.ril.enable.dtm : Only set this to 1 if your network allows simultaneous transfer of Circuit switched (CS) voice and Packet switched (PS) data over the same radio channel (ARFCN).