I wouldn't even think of trying to install Mojave on a brand-new MBP.
I'd just use it with High Sierra for at least a month or two, to be sure everything else was working ok...
I actually feel the opposite, I was too afraid to install Mojave on my daily driver machines yet (namely, a 5K iMac and 12" MB) but I've ordered a 2018 MBP which I might actually install Mojave on sometime during the first few days after its arrival.
My thinking is: firstly the other two machines are my daily drivers right now and while the new MBP will certainly replace them in this function sometime, it's not a device I'd rely on for the first few weeks so I'd have less to worry about with it than with the other two machines. Secondly, if something about the Mojave beta
does force me to revert to High Sierra, then it's much easier to re-setup a relatively new machine where I haven't customized and tuned everything yet than on one where I already have all my files and the like on.