Hello, electrically they are the same except for the power they handle that in the 1800 is greater, the only thing different is the type of pins that in the 1700 goes in L format, and the 1800 in 9-SIP format, if you can accommodate the pins folding them no problem.
Not because if you have the 1700XSL as you mentioned it comes in L format, and the other does not, you have to bend the pins to adapt it and be able to screw it to the heatsink.