I can't speak to the formal approval of Excel as the W&B means, but I certainly have seen it used many times, and have used it myself for many different aircraft. It is my opinion that as long as you can demonstrate that you did an accurate and correct W&B, the authority is not going to question how you did it, as long as there is evidence that you did! (Print a copy)
I particularly like that you can condition the cells to give you red text if something is out of limits.
Always do a reality check of the outcome, does it make sense? Particularly if you're having to leave seats empty to make your C of G, does it seem logical? What do other pilots of that type say? I have found many errors in the basic W&B for an aircraft over the years, which resulted from errors at weighing, or calculation errors for small amendments. Most commonly are not weights, but errors in fuselage station locations for calculation, or scale location. If you're finding errors you can't explain, go back a few W&B for that aircraft, and review the results...