Eh, of all the reasons not to run mixed cabs, IMO the most important is uneven power distribution. Your rig is only as strong as its weakest link, in your scenario, it's the 210. Running the 410 and 210 at the point where the 210 is safe, is leaving a lot of the 410s potential on the table.
In most cases like that, with the exception of the benefits of actually physically raising the 410 a little closer to ear level (but don't do that or you'll be less likely to hear the 210 farting), you'd probably be better off just running the 410 by itself and simply pushing it a little bit more. Just my 2c.
EDIT: I failed to realize that the 210 that you're talking about is your 1001RB combo. If that's the case, and the option to run the 410 on its own isn't possible, then I guess that changes things a bit. In that case, while you won't be able to really get the full potential out of the 410 with that pairing, it'll still be a good improvement over just using the combo on its own. Another 210 in place of the 410 would likely do nearly as much, with half the size and weight, but given your gear, I wouldn't fault it.