Get the handguards.
I've done both with and without and with good winter gloves. Yes the heated grips work, but not enough when it's really cold and if you take your hand off the grip they will cool down quickly. Add rain or fog to the mix and it is one of Dante's levels of He!!.
get the guards.
I have the GS guards on my bike now, and I did over 500 miles in mid 30s weather heading due north on I 55 at interstate speeds with a strong N wind. I think at the end I was hypothermic--even with multiple layers and a Gerbings heated vest, but my hands, though cold, were NOT numb and they were not what was chilling me. the guards did that.
BMWs are all about function. Get the guards; get some that are protective, and any concern you have about looks will disappear.
I rode my Stella! nearly 100k miles without guards and the measly 2500 I've put on Blanche have made me a believer.
You might consider ski mittens also.
John