In my opinion, there ought never be another 240/120 Delta system installed, ever. 208/120 Wye is the only way to go. You just can't beat having a real neutral.
Appliances and motors are, by NEMA conventions, intended to operate within 10% of their nameplate voltage. Combine this with the fact that most 208 services actually deliver closer to 212-215 volts, and a 230v rated appliance ought to do just fine.
Yes, heating elements will be affected, and in many cases the appliance maker will have 208v elements available. (I encountered this with a restaurant 'booster' heater, that had been ordered for the wrong voltage).
One blessing of three phase is that motors now require motor starters. I say this, because the new ones have electronic overloads ... and incorporate low voltage protection, phase imbalance protection, etc.
As for the panels .... what you do is determined by the service the PoCo gives you.
If they give you Delta, the original panel stays - but is fed by a new 'main' panel. You must do this to stay within the listing of (strangely enough) the three-phase panel; the fine print will tell you that UL doesn't want single-pole circuits in a delta-fed panel. I suppose they want to require a smarter idiot in order to mess things up.
If you're given Wye, then it's panel change-out time. You can't very well have a hot leg pass through the main panel, can you?
I'd avoid the 'triple split' arrangement like the plague. Apart from the balancing issues, you have the very real chance of some circuits - especially after a few remodels - having conductors (especially neutrals) divided among several panels.
