You won't know until its been in your box for a month or two unless you do a lot of electrical then maybe sooner, but either one I bet will sell for a fair price used on ebay.
The PP3 may be able to do many of the things functionally using the speaker, but that big display on PP100 sure looks nice ***. OTOH I bought my PP3 from Amazon for $95 shipped and the PP100 looks like 145E or about $220 USD and gotta figure ZERO warranty unless you like shipping etc to the UK.
More than anything it makes me hot for the PP4 or PP200, that next gen tool should be awesome when it gets here.
*** Once you have some experience listening to sensors, the sound of a bad one might be very obvious vs a good one. Same though might be required with the scope.