Seriously, though - you'll probably like it. But the question you should ask yourself first is: do you really need a flanger? After all, you listed three completely different pedals.
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Bassist for Vernian Process
Founder of the Lefty Union
Since you already have an ME50B, buying any of the pedals you listed will be redundant. However, I think that the env filters in the Boss multi aren't really very good so I will suggest that you get an env filter like a Qtron.