The Harbeth is more "natural" and "musical" and will be enjoyable on a wider range of recrodings. You don't find many Harbeth owners unhappy with their speakers. I would love to have a room big enough for the M40s, but the HL5s are proabably perfect for most normal size rooms (12x18 or 20). Will you loose out? Doubtful you'll feel that way - though the HL5 proabably don't go as deep as the Thiel. A more "musical" and "natural" option while maintaining the phase coherency and time alignment you are use to (these type of speakers seem to soundstage differently) are a pair of the Vandersteen 3A Sig, which will indeed be as full-range as what you are accustomed to, and very frequyently matched up with 100 watt Audio Research amps. Add a pair of 2Wq subwoofers and you have one hell of a good speaker system.
