Others do the festival thing, and enjoy it.
Consider how important it is to you, to see a lot of bands. Consider also that in order to be worth the $$ you will have to see a lot, and you will be busy all day at Flatstock.
not to mention...there are several hundred free shows that go on every year during SXSW. Texas Rock Fest, in particular, has been going on for 14 years now...is free and has several stages on 6th street during SXSW.
if you have a booth monkey, almost every band that will be here plays during some free day show. after flatstock every night, there are gatherings, bbqs, free shows in east austin, south austin, the freakin dog wash even. crazy.