I would say it is very worthwhile, raising the rear puts more weight on the front of the bike which makes it turn in quicker to very noticeably improve handling, as does raising the forks through the yokes by ~15mm. The jack up kit also slightly adjusts the suspension geometry making the rear shock a little firmer which is also useful if you haven't replaced the rear shock yet. I have tried both 25mm & 50mm jack up kits on the Gen1 the 25mm works well with raising the forks through the yokes but the with the 50mm this puts too much weight on the front from my experience, so it is best to use the 50mm kit with the forks in the standard position.
