IWDA (Msci World) Vs VHVE (FTSE Developed World)

I was considering investing into VHVE due to the lower TER as well as greater geographical coverage (Korea, Poland).

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However, my main concern is the fund size of VHVE is significantly lower than IWDA. Is that a logical/valid concern for the long run?

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Please let me know if you have any other opinions, still learning as well. Thanks in advance (:

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