With respect to Chef Brown:
I don't know about a "choux base." By definition a savory souffle is based on a stiff bechamel, and a sweet souffle on a creme patissiere. I wouldn't think you'd want the water that is part of choux paste (pate a choux).
I also don't know about "overworking." If you're over-beating your egg whites, that's something that usually give you trouble when you're trying to fold them in -- they get tough and just won't incorporate right. On the other hand, if you're over-mixing when folding in the whites that knocks the air out of the whites and results in a flat souffle
Regarding the cracking/liquid thing, a few things spring to mind.
Your oven may be too high and/or too inconsistent. You might try cutting your temp by 15 deg F and compensating with a skosh more time.
If its with the spinach/gruyere souffle -- you may be inconsistent in the amount of liquid the spinach is putting into the mix. One fix is to use frozen spinach -- which gives up its water more easily. (I find frozen spinach is superior to fresh whenever moisture content is an issue which includes anytime a bechamel is involved, including for creamed spinach.)
Another, related to the too much water problem, but going to both kinds of souffles is not enough flour in the souffle bases. Stiffen your bechamel and/or creme by upping the amount of flour slightly. The "classic" proportions for a souffle bechamel are 2 tbs butter + 2 tbs AP flour and 1 cup milk (infused with onion and bay); and for a souffle creme are 4 yolks + 4 tbs sugar + 2 tbs AP flour + 8 oz milk + 2 oz 1/2 and 1/2. I'm assuming you know how to make both of these -- but if you need more instruction on technique, just let me know.
Some other thoughts:
Don't use too much butter to fix the flour or sugar on the sides -- the point of the flour or sugar is to prevent sticking as the souffle rises, and makes for better service because the diner gets that good side-crust, and most important of all, easier clean up. Hey, priorities. But I digress. Let's return to the overly technical world of souffles. After you get the whole thing greased and floured or sugared, use your finger to put a heavy ring of butter around the top 1/4" of the inside of the dish. This is the pro's way to get a "top hat" effect going. Better looking, better rise. The other way -- a little easier -- is to use the tip of your pallete knife or a spoon to draw a ring around the outside.
No matter how you handle them, souffles sometimes crack, especially the sweet ones. Just dust them with powdered sugar or punch the center in at the table, and pour creme anglaise or chocolate sauce in the middle. Trust me, the cracks will be a thing forgotten.
Hope this helps,