Concern over fluoroacetate. Hopefully nothing, but still, I want to know where that F- goes, metabolically speaking. Or nephrotoxicity if the defluorination produces fluoride ion. Shulgin's publicised route in PIHKAL doesn't use fluoroacetate, but TFA anhydride, but bugger knows how the chinks would choose to do things. Can't say I have too much faith in their benign good will and talent.
Amounts of fluoride liberated probably wouldn't be sufficient to really do any harm from the projected dose levels of this one, but if theres any chance of fluoroacetate being liberated in vivo, or lurking as an impurity I'd not want to be the poor cunt that finds out.
Edit-re-even number of fluorine atoms..no, its the length of the carbon chain. Fluorine is generally pretty damn hard to rip off things metabolically speaking, but it does happen in some cases, such as some of the fluoroether inhalational anaesthetics, and iirc halothane also. But I don't know of (which isn't to say there are none) any polydefluorinations of similar substrates (e.g TFA isn't metabolized to fluoroacetate)