Oddly enough i've been looking at the Mustangs recently - can the trem be locked though? As it happens i have two HHs, the regular and the baritone. This is because i hate trems and prefer humbuckers for most things - although i'm thinking of getting them coil tapped to get a more Fenderish tone out of them occasionally. i'd get the Jag now and maybe get a cheap Mustang later. Of course if you prefer humbuckers then there's no standard Mustang with them i don't think.
Actually i wouldn't mind a regular Jag now, my mate bought one recently with a Mustang bridge already installed and with the trem lock button it makes a good single coil alternative to the HH - i don't think the Mustang has a trem lock though.
Have you guessed yet - i hate trems 😁