Reading Jeff Bergeron's posts might also help steer you toward some appropriate choices. Some suggestions for trying boots out in shops:
1. Check how different boots fit, without the liner but with your footbeds in them (if you use footbeds) as well as with the liner in. Any place your foot touches the shell with the liner removed means a problem that will need to be fixed or it will almost certainly cause painful problems when you are skiing.
2. The thicker the liner the more it will usually pack out, and often in just a few days of skiing. Very tight in the shop is no problem but pain or hot spots will likely be. Since your foot spreads out throughout the day, the best time for trying on boots is in the afternoon.
3. Your foot should come quite close to the sides of the the boot with the liner removed without actually touching them, just a few mm's, not much more. Also, leave them on for a while in the shop with the liners in to see what develops.
4. A common rule of thumb is a 3/4's -1 finger space between your heel and the back of the inside of the boot for a "performance" fit or 2 fingers for a "comfort" fit. In the right boot a 3/4's- 1 finger fit should still be totally comfortable when skiing. Racers commonly go for a 1/2 finger or even closer fit. Finger size is relative but you get the idea. Usually, this means going down at least one and frequently two full sizes from your street shoe size. If your toes touch the front of the boot with the lines in, flex to seat your heel in the boot and see if it eliminates the problem.
5. Shell flex means little in the shop at warm temps. so you will need to quiz the bootfitters about that. Some boots stiffen up in the cold much more than others. There really isn't much standardization of flex indexes between manufacturers much like is the case with ski trails (blue, back etc.) among different ski areas. It's mostly relative within a given manufacturer's line.
6. Find the boot that comes closest to your footshape and intended uses and then have whatever modifications made that you need.
7. Good boots that fit properly much more important than good skis and last much longer. Knowledgeable, talented bootfitters are, unfortunately, much more the exception than the rule. But check out Epic's list of recommended bootfitter's to see who might be listed in your area . Good luck.