There are advantages to look-up and look-down depending on the tactic you're employing. It might work well against a radar with a known vulnerability to this type of maneuver, although I'm not sure I would employ it as a general tactic against generic Doppler radars (ignoring kinematic issues here, but they're very much a concern even if the maneuver is both doable and effective).

There are plenty of other ways to skin the cat that I would suggest reaching for before this. We've been fighting with and against Doppler radars for a long time...