It would be faster yes, with our 1612, once it has finished cutting a segment, it takes about 45 -60 seconds to turn off the vacuum, advance the media, turn the vacuum back on and read the next batch of crop marks and start cutting again, with a larger bed it doesn't have to do this as often. I can't see accuracy being affected, my 1612 cuts bang on where it's supposed to every time.
It's up to you to decide if saving 2 minutes per sheet is worth the added expense. If you plan on getting the router attachment, the larger machine would be a good choice, so you don't need to deal with 4x8 sheets hanging off the front and back of the machine, we use an outfeed table when processing sheet goods on ours or else your parts fall on the floor when the sheet advances.