For telecommunication starters, the 700MHz digital spectrum has better propagation than higher frequency spectrum such as 1800MHz spectrum, and better in-building coverage. The cost of achieving equivalent network coverage is significantly lower using 700MHz spectrum compared to 1800MHz.
However, risks would revolve around the evolution of the eco-system for 700MHz. If it becomes a key LTE frequency, handsets and network equipment development will be prioritized for it (even if the channel alignment is slightly different to 700MHz LTE.