There's a lot of good discussion in all of the preceding posts, all of it true.
Having been around and in the industry at the time that the mechanics of Wind Shear were being understood, and associated Avoidance and Recovery procedures were being developed, the generic procedure for all aircraft, irrespective of transient drag rises during gear retraction, was that the gear would absorb a huge amount of impact energy in the event of ground contact. Given the choice of flying into the ground with the gear UP or DOWN, this writer would firmly opt for the choice of leaving the Gear DOWN.
If it's a Light or Moderate wind shear encounter, Gear UP would undoubtedly be the best option, ground impact is not a factor, but in these cases, the aircraft performance would well cope with the additional drag. In a severe encounter, however, where ground contact is a significant factor, your chances of survival with the gear down are immeasurably higher.
The one generic procedure that befuddles me, is the recommendation to takeoff with the highest possible Flap setting if wind shear is a possibility. In a lower flap takeoff case, with stall imminent, selection of a higher flap setting will then give me increased stall protection. There is at least one recorded case where a Fokker test pilot opted for a lower flap setting, and "saved the day" by selecting the next highest flap setting to avoid ground impact.
Any comments on the latter?
Regards,
Old Smokey