Your current temp probes are most likely 10K ohm thermister type probes. The most common is type N. The 3 wire probes you are referring to are RTD sensors and they are in no way compatible.
If you bought a good PID, like an SYL-2352, it will accept most types of probes including the TC-N and RTD types, BUT, you would have to hook each up individually, and program the PID every time you wanted to change between them. That would be inconvenient enough that I wouldn't even consider doing it.
You pretty much have to stick with one type or another. Visit
www.auberins.com and look at their probes. Pretty much the nicest probes I've found. They offer an upgrade to most of their probes, which consists of a pannel quick disconnect (from your PID to the outside of your pannel, A quick disconnect 6-12 foot cord from the pannel to the probe, and a quick disconnect on the probe itself so you can disconnect it and wash the kettle away from the controller. I think the upgrade is $11...well worth it.
hope that helps.