I start with kart in 89 then do auto-x then switch back to kart. Last year I do 2 auto-x and 3 kart. Both of them are fun.
Pro and Con
Pro Kast is real racing with other kart. Nothing beat the rush that 10 kart go to the first turn together and want to be in the front but only one come out in the front Kart you can race 3 heats + 2 practices more track time. Downside is you have to have a kart and lot of practice if you need to be upfront.
Pro Auto-x is you can use your daily drive and have everything done in half a day. But you race with time and yourself (one on the track) and only 4-6 runs less than 10 min of track time.
Hay do both like me