The key is the match. I used to have a pair of Maggie 3.5R's. I found them as responsive as a giant hunk of granite. They loved the power and took a high current to drive. When you hit the sweet spot though, wow. It was such an exact speaker that you could hear people talking in the background of lots of the Beatles recordings. After several other trades and evolutions, I moved to the Altec Lansing A7-500's (16 ohm). Tried these using the same amp as the Maggie's and felt the sound quality went down. The horn could be piercing and the woofer wompy. When hooked up to a 6 watt SET however, its the sweetest, most wonderful sounding system I have ever heard, a true toe curler.
The horn sound that was there using the higher power amp went away and the bass is a sweet reach around hug. This combination actually sounds good at lower volumes and gets adequately loud enough that my wife can hear me, from our second floor, very well, from a sound dampened basement (I blame the hvac). If you are buying new, you need to ask to audition. If its a really good place that you have done business with, this shouldn't be an issue. Otherwise, load up your amp and other accoutrements and head to the store. If still denied, buy somewhere else. I view this as going to buy a car without a test drive. What some places want you to do is sit in their car and just say vroom, vroom and imagine. Get as close as you to what your system will be prior to buying and believe your ears and not someone else's. The Cornwall's as sensitive as they are, they just need the proper amp. Using pipes as a metaphor, your Maggie's are like the drain pipes coming off of Hoover dam and the Cornwall's are like the pipes in a cathedral organ. Each beautiful but totally different.