When I started DIY CO2 and had a cheap needle valve, I almost gassed my fish twice. I went and bought a more expensive needle valve, I almost gassed my fish a third time. This was due to the needle valve and CO2 set up supplying a very inconsistent amount of CO2. sometimes really low, then other times really high.
I added a $10 Tetra air pump and a timer, and have not had any issues gassing them since, even when the CO2 gets out of hand. So yes, for me, it was completely worth not having to worry about my 10 rainbows, 6 cories, and 2 fancy plecos, plus the handful of amano shrimp.
Love your tanks and they will love you back