So based on the posts I've seen throughout this thread, we only have a single viable alternative and that is the 1600mAh battery? I also tried opening the Mugen website but it seems to be down.
I'm looking to have greater capacities for my Xperia Active and what I use it normally for is just FM Radio (on my way to work), a few minutes to an hour of gaming when I get home (ShadowGun, Cut the Rope), internet (to check in to Foursquare, check email, etc), SMS.
With the above usage, I get around almost a day of battery power. I'm not entirely sure though because when at the office I tend to charge it while I'm working so that I'm sure it won't die on me while on my way home.
I don't have 3G connection or any data plan for that matter since I'm almost always around a wifi hotspot so I don't see a need for one.
Any tips to up the battery to at least 2 days of usage? As far as this thead goes, I have't read a solid feedback on the 1600mAh battery which I'm looking forward to purchasing.