1.4 or 2.0 extender?

Anyone that uses the Canon extenders either 1.4X or 2.0X, do you miss not having the f2.8 on the 70-200? Also, any pro's or con's about just getting the 1.4X? They are the same price, just never used any of them. Thanks in advance.
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John

Glenwood Springs, Co.