well, technically, this statement "the analog out of the V3 runs about 10-15db hotter than the digi out" is not true.
when running a balanced line out, the max analog output (when the internal A/D hits 0dBfs) will be +25 dBu. If you are running into an unbalanced connection, the max analog output will be +19 dBu. It is true that a lot of gear can't take that hot of a signal, so its definitely a good idea to know the specs of the gear you run behind the V3. (for example, when running line-in on the 722, the 722 will hit 0dBfs with an analog signal of +20dBu. because the 722 has an adjustable line-in, you can set the 722 line-in to -5dB. At that setting, the 722 will hit 0dBfs at +25dBu, which is exactly what the V3 will be outputting when the V3's own internal A/D hits 0dBfs. because of that, the two recordings will have exactly the same recorded levels.) I know you said that you were running into a tape deck, but I thought the 722 was a good example to show that it largely depends on the gear you are using, and it is not a set rule that "the analog outs are about 10-15db hotter than the digi out".
the other thing to keep in mind is this. if the polarity of the digital outs has not been fixed, the digital output will be 180 degrees out of phase relative to the analog outs. If you're not planning on mixing any of the signals afterwards, it probably doesn't matter. and if the V3 digital out polarity has been fixed, then you're all set as well. Just one more thing to keep in mind.