but it’s being sold by a local store known for poor after-sales service.
local store offering excellent after-sales service.
After-sales service is only needed when something is wrong with the hardware you bought. Good/great quality PSUs last a decade and i don't think you'd have issues with good PSU, to warrant a RMA (warranty claim).
E.g the Seasonic units that i've used and still are using - none of them had any issue.
My Seasonic PSU portfolio (from oldest):
S12II-520 80+ Bronze - bought brand new, in use for 3 years (had 3 year warranty), now retired.
M12II-850 Evo 80+ Bronze - bought brand new, in use for 5 years (had 5 year warranty), now retired.
PRIME TX-650 80+ Titanium - bought brand new, in use for 9+ years (has 12 year warranty), still in use, powering my main build, Skylake.
Focus PX-550 80+ Platinum - bought brand new, in use for 7+ years (has 10 year warranty), still in use, powering my old main build, AMD.
PRIME TX-650 80+ Titanium - bought brand new, in use for 5+ years (has 12 year warranty), still in use, powering missus'es build, Haswell.
(My builds full specs with pics in my sig.)
So, with good quality components, chances that it dies within warranty period, are slim. And unless you know for a fact that you are facing issues (e.g buying cheap hardware), there's no reason why to stress over after-sales service issue.
Personally, i'd go with MSI unit due to better build quality (heck, i'd go with Seasonic instead or Super Flower if no Seasonic is present).