I also have a TX816. I don't have an DX7 mk1 currently but I do have a TX7. I also have a TX802, DX200, and the DX PLG card in Motif ES Rack

I did a bunch of comparisons between the Arturia DX7 V, Dexed, my hardware

My TX816 and TX7 sound pretty much exactly the same. The TX816 is a touch cleaner but I think that is due to the Balanced XLR outputs. The TX802 sounds even cleaner while the PLG and DX200 sound pristine like a VST

I found the Arturia DX V to be much closer to the original hardware than Dexed. They clearly modeled the behavior of the DAC better

Interestingly enough was when I stacked 8 instances of either Dexed or the Arturia DX7 V it didn't produce the same rich chorus sound you get when you stack all 8 modules of the TX816

The truth is that the software emulations sound spot on in most cases but there are situations where the old hardware simply sounds unique, especially when stacking sounds or multi-tracking where the minuscule nuances add up.

I personally always choose the original hardware as many of my programming techniques rely on the nuances only done well in hardware. It's not necessary to make great music, of course, but it's a preference based on experience.

I wonder if it’s because mixing them before passing them through the the same dac. Also the digital summing might be different than in the daw.

How about getting a TX802? That’s the module of the DX7ii.

It won’t be quite as gnarly as a DX7 maybe, but the difference won’t be much. You’d have portability, front panel tweakability (tho it’s a little clunky), and Yamaha 6 op FM.

Obviously touring old stuff carries some risk. But if the current options don’t work for the OP, this might. Could always carry a spare 802 on the road, they’re not big, nor usually expensive nowadays.

A working synth made in Japan in the 1980's - I wouldn't consider it risky. I'd be more concerned about the reliability of the new stuff.