Yeah, there's def the upfront cost, which not everyone can justify. Though, at the same time, a lower-amp-hour battery can provide as much actually-usable energy as a higher-amp-hour-rated SLA battery (so you could purchase a LiFePo4 battery with a lower amp-hour rating than the equivalent SLA battery but still get the same run time). I wouldn't know how much lower you can go though offhand.