I ran an Imp 1B (we were using custom machines, I just did mine as a 2E that had been coincidentally customized to match the 1B) in a mercenary campaign earlier this year. It was great: I'd march it out onto the field, choose a spot I liked, then sit there and deliver LRM and PPC fire to everything in sight. If they got close, the medium laser array and ECM kept them honest.
And, of course, shouting "Oh yeah!" whenever I forced my way through a building in a city fight was fun, too.