If you plan on listening to the simulcast P25 trunked systems...probably, yes. The only Uniden scanners that are purpose built to handle decoding of simulcast P25 trunked systems are the SDS100 and SDS200.
That doesn't mean the HP-2 won't work, it just means that your mileage may vary greatly depending on your location relative to the nearest subsites of each system. In some cases, less is more, and so an outdoor antenna might be counterproductive.