I have done this. 4 caps ABE + 2 AB / day. Absolutely loved it. Is it necessary? No, because I still found 4 ABE or 4 AB caps to work phenomenally. However, if you've got the extra cash I suggest you try it.
I actually heard of someone using 8 a day lol.
I actually just added ABE into my current stack. Here's what I'm doing.
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Week 1: 4 ABE / Day
Week 2: 4 ABE + 2 AB / Day
Week 3-6: 4 ABE + 4 AB / Day
Week 7: 4 ABE + 2 AB / Day
Week 8: 4 ABE / Day
I'm running this along with Erase Pro, Alphamine, Test Powder and Compound 20. Plus a few other goodies.