There are several differences between the GPX 5000 and the SDC 2300:
1) The SDC 2300 is fully Submersible up to 10 Feet (3m) of Water and the GPX 5000 is not waterproof.
2) The GPX 5000 has a longer battery life of 25 to 30 Hours than the SDC which only has 6 to 8 hours.
3) The GPX 5000 has Dual Voltage Technology (DVT) which ensures an Accurate Ground Balance to Provide Maximum Sensitivity and Depth in All Ground Types vs the SDC has Automatic Ground Tracking (AGT) for Fast Ground Balance.
4) The SDC 2300 can collapse small enough to fit inside a backpack vs the GPX 5000 can not