A 400 hour guy/gal is just as cape able as a 1000+ hour guy/gal at handling the 121 training environment. You're either a good pilot or have the potential to learn and apply or you're just not cut out for it. It's all about what type of pilot you are. There are plenty of low time pilots that fly 10x better than guys with 5k+. I say if you know you can handle fast paced, tons of systems info, and simulator environments then apply! What's the worst they could say, no or not respond?

Usually the pilots you find on here that discourage low timers from applying more than likely had problems themselves.