Tex- Glad to see you investing time and effort into research before you buy. You're correct about going with a mid-fat for where you're going to be skiing. Western snow is soft enough that you don't need 60-something under foot to get a good edge grab. My biggest suggestion to you is to get out on a new pair of skis as soon as you can, so you can get a good feel for them. If you're going into an intensive week long clinic, you want to be comfortable on the gear you're skiing before you start it. Having taught those types of clinics before, I can tell you that they really are what they say they are, intensive. Off the bat, you're going to have instructors breaking down your skiing into minute detail, and then giving you tasks to do to improve everything. You'll spend a run doing pressure drills, another on stance, another on edging, another on hand position, another on where you're looking (i'm not kidding)... and on and on all week. With all that going on, the last thing you need is to be distracted by having to acclimate yourself to new equipment. Even if its only getting a morning in on them, it'll help you get an idea of what the skis are like with your technique now. It also gives you a better idea where the changes are coming from, the equipment or the technique. You probably won't be doing anything the same after the week you'll have, so everything will feel different.
Also, a couple pointers going into your clinic week. Like I said, you're going to be attacked from all angles about your skiing. Needless to say, all the criticism you get will be constructive, so do your best to take it as such. Also, you're going to be given tons of information in a very short amount of time. Ask your clinicians to write down the drills you are doing, so you can have them to repeat after the clinic is over. We instructors are not wild about writing things down, but as it's an intensive clinic, your clinicians will be hoping for a nice tip at the end of the week, and will definitely do it for you if you ask. Oh, and another thing... be nice to your clinicians and tip them well. We don't get paid nearly as much as you might think. Last but not least, a nickel's worth of free advice. On a number of occasions, you said you're intermediate, and want to become an expert during this clinic. Probably just lack of terminology knowledge, but you're not going to become an expert in the course of a week. You may become more of an advanced skier, but expert is beyond advanced. Gaining expert ability takes years, and literally thousands of hours and millions of turns. So don't be discouraged if after the week you're not quite ready to ski a 60 degree back bowl. Sit-crawl-walk-run-ski. It takes a while, but keep at it, because with enough work, just about anybody can get there. Good luck, and have fun!