Hi Robert,
Form a quick look at what I can determine:
1000BaseT-SFP-GLC-T (GLC-T) - is a 1000BASE-T SFP transceiver module for Category 5 copper wire
DS-SFP-GE-T (SFP-GE-T)- is a 1000BASE-T SFP transceiver module for Category 5 UTP copper wire but has extended operating temperature range and DOM support (RJ45/100m/1.25GBd/1Gbps)
So it seem a straight upgrade
Of which the DS-SFP-GE-T is compatible with MDS9216i - couldn't say for the MDS9506 sicne you haven't mention the lincards fitted.
Hope this helps
MD
Reference:
http://www.cisco.com/en/US/docs/interfaces_modules/transceiver_modules/compatibility/matrix/OL_6981.html
http://www.cisco.com/en/US/prod/collateral/ps4159/ps6409/ps4358/product_data_sheet09186a00801bc698.pdf