The other posters are pretty much right. The Klipsch/Magnepan comparison is dogs and cats. The thin sound you heard could also have come from a couple of things: If the pair in the shop were new and not run in that would explain a lot of the brightness you heard. Magnepan speakers need about 200-300 hours on them to open up. The power was adequate for the most part. Was the room a large one, with a lot of hard surfaces. Properly powered and set up Magnepans are capable of very respectable bass output. Of course, I am also making this claim based on living with the much larger MG 3.6R. But, I also have a pair of MMGs which make a very nice showing of themselves in the bass department as well.
You have a very nice setup as it is. The sound of the ultra high efficiency Klipsch is very different from the classic Maggie sound. I am willing to bet that if you have the opportunity to listen to a good Maggie setup for an extended time with music you are familiar with, give your ears a chance to adjust to what you are hearing, you will discover that the bass is there and that it is very accurate, the midrange is true to the source and there is a seamless integration of the sound. That said, you may also discover that you prefer what you have. There is no denying that Magnepans are fussy to set up, crazy power hungry beasts, and the bass does not move air the way a cone woofer can, but make no mistake, they can do bass.
You have a very nice setup as it is. The sound of the ultra high efficiency Klipsch is very different from the classic Maggie sound. I am willing to bet that if you have the opportunity to listen to a good Maggie setup for an extended time with music you are familiar with, give your ears a chance to adjust to what you are hearing, you will discover that the bass is there and that it is very accurate, the midrange is true to the source and there is a seamless integration of the sound. That said, you may also discover that you prefer what you have. There is no denying that Magnepans are fussy to set up, crazy power hungry beasts, and the bass does not move air the way a cone woofer can, but make no mistake, they can do bass.