I have a book about JG 26. A young pilot named George Genth gets into trouble with his 109 K4 with ice on the canopy. He gets disoriented and the 109 goes into a dive. The last speed he saw was 750 kms. He finally got his bearings at 1600 meters when the ice thawed. He pulled out around 200 meters. He didn't say anything about the wings or being worried about them flying off.
Here it is again read the....Diving - structural rigidity of 109 in dives..This has to have some truth to it because these men flew them.
http://www.virtualpilots.fi/feature/articles/109myths/