The main problem with a VP1 is that it's virtually impossible to get spares or new accessory transmitters for it. That said, the rain gauge and anemometer are compatible with the equivalent VP2 parts (though not the temp/hum sensor).
Beyond that comment, I'm not sure quite what question you're asking. No harm at all in keeping the VP1 going for as long as it can be maintained, though whether it's worth spending money to replace eg rain gauge or anemometer is debatable (though they could be used as spares for a replacement VP2 of course).
But if you wanted to eg add new temp/hum, soil moisture etc sensors or to explore new options for data handling such as Weatherlink Live then you're going to need a VP2 for that.
