According to the Front Mission Evolved FAQ, a little more than 10 hours.
Good thing Front Mission Evolved has online multiplayer. Front Mission Evolved includes deathmatch, team deathmatch, and domination modes. The game also supports voice chat for online matches. People who pick up the PC version will battle over Steam, not Games for Windows Live.
Reminiscent of Front Mission 4, Front Mission Evolved only has English voice acting… even in Japan. The Japanese version has English voiceovers and Japanese subtitles.
Front Mission Evolved stomps into North America on September 14, a few days before it launches in Japan on September 16.