Is it better to play a marimba with graduated bars?

I'm a senior in high school and have been playing mallet percussion instruments in band for 6 years. I recently decided that it's time for me to actually buy my own instrument if I want to improve any more and I have a very special passion for the marimba, so I mentioned this to my band teacher and he really wants to help. The problem is that he insists that it would be of my best interest to buy one that has graduated bars, and I've only played an instrument with graduated bars once in my life. Non-graduated bars are way more comfortable to me and this is a pretty hefty investment so I don't want to make the wrong decision and end up playing an annoying instrument for no gain. So is it really more beneficial to me to buy a marimba with graduated bars and if so why? I'm willing to buy one and play it if it really is beneficial to become a better musician, but I don't see why he insists so passionately that I buy one instead of one with non-graduated bars.

TL;DR: Band teacher insists that I buy a marimba with graduated bars, I've never played one like that and don't want to, but if it really will help in the long run, I'd be willing to buy one and get used to it. Another voice with more expertise in this sort of thing would help tremendously. Thanks.