It's not only brand specific - it's model specific. My Rossi T-Power shorty slaloms are 160, just the perfect size for me in that model. My Rossi Bandit XX's are 170 - again, the perfect size for me in that model. In some models, going up or down a size just doesn't work for me, while in others, it works.
I have enjoyed the K2 Mod 7/8 [now called "Axis"] in 174 and in 167. Both work for me. The 167 is a bit more maneuverable, while the 174 had better float and stability. That's about the trade off: If you can handle different sizes in the same model, going longer can yield better float and stability at the expense of maneuverability, while going shorter can improve ease of maneuvering while giving up some float and stabilty.
You might want to consider first the kind of skiing that you want to do, including the range of versatility you need, and then determine what model you want. From there, skiing on them will tell you which length you like. If you were ALWAYS on groomers, a shorty slalom might fill the bill for you because they're short but they're MADE to be skied short. If you ONLY were in the back country in deep snow on big mountains, a true fat ski would be better, and it would probably be recommended in a longer length. If you need versatility, will you be skiing mostly on groomers with some off-piste, or will you be skiing mostly off-piste with some time spent on groomers? If you spend time off piste, is it in waist deep powder, or is it in moguls or in trees that have had paths skied through them?
In my own experience, versatility has been a function of the model of ski. Length then becomes a matter of trial. For me, in my own experience, the mid-fat range [70 mm waist to 80+ mm waist] in about 170 cm seems to be most versatile. But in a particular model, I could only know the best length for me by on-snow trial.
Let us know what you discover in your search.