I had the exact same fear, and I even posted a "What if I don't like it?" thread over on AGF. The only thing I can say is this: if you do your homework regarding tone woods, body size, scale length, etc., you'll likely get a guitar that blows you away. That was my experience. I knew my BTO was going to be good, but I wasn't quite prepared for just HOW good it turned out. I knew from the first strum that this was a guitar I would have for the rest of my life.
There are no guarantees in life. . And, just for the sake of hypothesis, let's say the guitar doesn't live up to your expectations, you can always sell it. There are plenty of eager buyers out there for a lightly used custom guitar. But that's a worst-case scenario.
I agree with Dennis, but it is still nerve wracking; especially after the order is in and the weeks of waiting result in many second thoughts. However, like Dennis says "you can minimize the risk by knowing exactly what you want"/
To shed some added light, I'll outline the thought process I went trough to come up with the "structural" BTO options for my Custom GC all mahogany.
1) I had a '97 512 that was super and had the wonderful woody mahogany punch to it. So mahogany was a good starting point, as was the GC body shape (I'm firmly in the GC, OM, 000 camp regardless of builder).
2) But, I wanted something less bright than the 512 that had an Englemann top; but I had owned a GC5 (cedar top) and found it was too soft and lacked some of the bass I was looking for. I also already owned an all mahogany Larrivee OM at the time I was specing out the Taylor BTO and the all mahogany configuration seemed about where I wanted to be. So now were at an all mahogany GC for the basic body components.....
3) I was still concerned about the lack of bass on the GC5 I had owned and remembered that the newer GC8 with the CV bracing had a noticeable tonal boost from the previous GC8's I'd played, so I added Sitka CV bracing to the mix. So far, so good.
4) I also like the neck profiles on the pre NT Taylors I've owned, and prefer the long scale to the standard GC shorter scale. A call to the customer service dept at Taylor led me to talk to some of the BTO guys and they confirmed that a T5 neck carve, widened to a 1 3/4 nut and lengthened to a long scale would be very close to the Pre NT necks (and my thinking was that the longer scale might also further enhance the overall tone and might add more bass, again)
So, the final was (is).....All Mahogany GC with CV bracing, long scale with a T5 neck carve. The rest of the options were just for looks (like mahogany with no stripes and special tinting to get the wine red color, etc.
How did it turn out....better then I expected The overall presence, and yes the bass is much more prevailent than any Taylor GC I've owned or tried (including the GC8 with the CV bracing) It's hard to express tonal qualities with words but I lilke to say that the tone of my old 512 made me want to sit on a bench, drink beer and throw peanuts on the floor. This BTO feels more at home being played in silk pajamas, in a leather chair in front of a mellow fire in the fireplace. It sounds just like it looks and the Taylor BTO folks made it that way.
Thanks, Taylor
http://www.nebelphotography.com/images/TaylorGCcustom/layside1.jpg