If you're only tuning down to E Flat, no problems are really going to present themselves. I'd recommend pick either Eb standard or D standard and leave it at that, it's just gonna be a fucking pain in the ass switching between the two.
You might have to make ever so slight adjustments to intonation, but it's certainly going to be nothing drastic compared to tuning it down to A and whacking a 13-64 set of strings on there.