Hi djapigo

Hi there are numerous topics on the subject of array formulas and I personally think it is down to the size of your workbook etc. Thou I might be wrong!

Read this link to Microsoft web site discussing the matter, the page also has 2 VBA timers to record how long each formula takes.
Formula: copy to clipboard 
http://msdn.microsoft.com/en-us/library/aa730921.aspx


From one John Walkenbach books:

The main advantage, of course, is that an array formula enables you to perform otherwise
impossible calculations. As you gain more experience with arrays, however, you undoubtedly will also
discover some disadvantages.
Array formulas are one of the least understood features of Excel. Consequently, if you plan to share a
workbook with someone who may need to make modifications, you should probably avoid using array
formulas. Encountering an array formula when you don’t know what it is can be very confusing.
You might also discover that you can easily forget to enter an array formula by pressing Ctrl+Shift+Enter.
(And don’t forget: If you edit an existing array, you must remember to use this key combination to complete
the edits.) Except for logical errors, this is probably the most common problem that users have
with array formulas. If you press Enter by mistake after editing an array formula, just press F2 to get back
into Edit mode and then press Ctrl+Shift+Enter.
Another potential problem with array formulas is that they can slow your worksheet’s recalculations,
especially if you use very large arrays. On a faster system, this delay in speed may not be a problem.
But, conversely, using an array formula is almost always faster than using a custom VBA function.
Kevin