The Mikro is 28” scale, isn’t it? More like a baritone than Bass VI.
True as far as tendencies: most VI (EADGBE) instruments are 30", most baritone guitars (ADGCEA, or BEADF#B) are 26" to 28".
The Ibanez miKro doesn't know nor care, of course, being that it comes tuned to bass-pitch (B)EADG from the factory. It's not like adding treble strings makes the scale suddenly unsuitable for bass tuning: whether or not it is depends on personal preference, as it measures against the specific compromise (which every scale length is, in essence).
28.6
Is the 1.4" really significant? String gauge determines tuning more for me than a small difference in scale.
Gretsch and EBMM (at least used to) make baritones in 30 and 29.625.
Conversely, the Fender Jaguar Baritone Custom from the early Aughts was tuned E to e and had a 28.5" scale:
en.wikipedia.org
I don’t know! 1.5” is pretty significant, though. I would expect intonation to be tough and the low E would probably be pretty floppy.
Baritones use regular guitar strings for E to B, so I’m not sure they’re really comparable. A Bass VI is an octave below that.
Intonation depends on saddle (and bridge-plate) placement: there are diminishing returns (the window of tuning stability and not-overly-inharmonic tone, for bass-pitch steel-core strings, closes the shorter the scale gets), but if you consider
there are 23" scale electric basses around, 28.6" is still bass-viable, if not for everyone.
As for floppiness, it depends on the gauge, which can be increased (at the expense of physical room at the lowest frets, marginally; as well as, for the lowest strings, of "usable", not-too-thumpy, chorus-free tone up the fretboard).
I do wonder what the string spacing would be like.
You don't have to: it would be wider than most VIs, with the 5-string MiKro (GSRM25) having a 45mm nut
GSRM25 at Ibanez. Ibanez offers electric guitars, bass guitars, acoustic guitars, effect and pedals, amps, plus guitar accessories like tuners, straps and picks.
www.ibanez.com
vs. the 42mm of the SRC6 both old and new
The SRC6 is a six string Soundgear series solid body electric bass model introduced by Ibanez for 2014. It was made in Indonesia as part of the Ibanez Bass Workshop line. Although a six-string bass, it's design philosophy is very different from others in Ibanez line, featuring a much narrower...
ibanez.fandom.com
The neck taper could even allow a 13mm spacing at the bridge, like on a Shergold Marathon/Eastwood Hooky Bass 6, vs the 10.8mm of the SRC6, if the OP were so inclined (in that case a different bridge, or single bridge elements, would be required).