low boost above 10k is a TSIO-550 thing... IO-550 users can't
make the power (need the flow) up high.

high boost is for priming... low boost is turned
on once the engine fires on hot start and roll out
on a hot day. (hmm, wonder if I should use low boost
on low power landing too... hmm)

my *guess* is low would be enough fuel if the engine
driven pump fails.. so your idea of (high) is
a good one.. the sr22 uses off-low-(high)