We used to run a DC242 then upgraded to a 700. In my opinion the 700 does give (slightly) better registration but Xerox would not recommend 'duplexing' 300gsm board and you would have to 'over-rule' the RIP settings to actually back-up 300gsm
The registration is +/- 1mm so can be 2mm out on the sheet.
And, in my opinion of owning both machines, the DC242 will lay down the toner (ink) a million times better if printing onto any kind of embossed board from Linen to Hammer Finishes.
We print similar items to you, we no longer offer any embossed card as a substrate and with hindsight I wished I'd kept the DC242 for this reason (without a contract) but I would also recommend the 700 as a quicker and more solid machine.
Hope this helps your in your decision.