I commute 25 miles round trip in New York City. I do go up some steep heals.I have a BionX 350 Watt motor and 10 Amp battery. I also carry around 35 poundsin my pannier’s bags with a heavy mountain bike. I have no problem going up thehills. I think the issue is the distance you plan on riding. You will not getmore than 15 miles on a charge if your ride is very hilly. However, if yourecharge the battery on riding downhill you can extend it even further.
For 2500 pounds you should have no problem. I have a Trek FX+ and a Trek 4300 with a BionX kit