The Wadi el-Hôl Inscription: Earlier than Serabit?

In 1993 Egyptologist John Darnell discovered in the Wadi el-Hôl near Luxor, Egypt, an alphabetic inscription similar to those at Serabit el-Khadem discussed in the accompanying article. Initially, it was thought that this inscription might be earlier than the Serabit inscriptions. If so, was the alphabet invented earlier than the Serabit inscriptions and somewhere other than Serabit, perhaps near the Wadi el-Hôl?