So what's your price range? Since you're looking at a Carvin is it safe to say you want to drop $700- $1000 on a 6?
If so, and you're not averse to buying used, you may be able to snag a used higher-end 6 for around $1K. Possibly a Warwick Corvette 6 or something.
If it's more budget conscious sixers you're looking at, I can make a bunch of suggestions:
These I've played:
Peavey Fury 6- Looks, sounds, and feels like a bass costing many times as much. It has the same electronics as the higher end Cirrus line, I believe. 2.125" wide at the nut, 3.25" wide at the heel. The neck is thin and fast.
Ibanez SR506- Another nice lower-priced 6. It has a darker tone than the Peavey given the 'darker' tonewoods. The neck is pretty sleek, but not as fast as the Peavey; but maybe that's because I'm more used to maple necks than wenge. Also 2.125" wide at the nut and 3.25" wide at the heel
Samick Fairlane 6- I have one and love it. However, the reason I love it is the reason many folks would hate it. Skinny neck. 2.00" wide at the nut and 3.1" wide at the heel. Possibly the narrowest 6-string neck out there, but it has dual truss rods.
These I haven't played, but have considered:
ESP B206LTD- the '05s now come with EMG pickups instead of ESP pickups. ESP is said to use good woods and their instruments are usually of consistent quality
Spector Legend 6- It's a Spector. 'Nuff said. 35" scale.
Schecter Stilletto- You don't see too many cats out there playing Schecters, but those who do love them. Their instruments are said to be good quality.
Yamaha TRB1006- A bit out of my price range when I was looking, but I know Yamaha 6s have dual truss rods and Yamaha instruments are consistently good quality.
Ibanez BTB- many folks prefer the BTB necks and feel over Soundgear.