I love the boss lift, have had it on my truck for a few years and have no complaints. You can either buy UCAs now or later, but they really make a difference in alignment and it does provide for more travel up front then the stock. The downside is a little more maintenance with them, uniballs may require even more maintenance. For example, I have found I need to grease the bushings on my Camburg Bushings about every 8-10k to keep them quiet. The cheaper UCA's option are the SPC light racing, it'll give all the caster you need for the lowest cost, but at times they've had some qiuality issues. There are plenty of options but none are cheap, my front is lifted about 2.5" and I was so happy when I replaced my UCA's, drove a lot better.
Look around for links on the different UCA's options, there are several lengthy threads, new are a couple...
http://www.toyota-4runner.org/5th-gen-t4rs/210010-285s-stock-trail-rims-uca-needed.html
http://www.toyota-4runner.org/5th-gen-t4rs/153031-how-do-i-know-if-i-ucas-new-lift-my-5th-gen.html