Poles for the flatlands, outside of avalanche country, are fairly straight forward. In avalanche country it gets complicated, since some poles have options for fitting avalanche probes. We will leave this subject to the mountain skiing resources, and focus on the simpler considerations for the flatland back country.
You want a very strong pole for back country trekking. Hill climbing, hauling a heavy sled, will tax the strength of your poles. Don’t even think of using ultralight racing poles – they will snap like dry twigs on a tough climb. Back country skiing poles are much stronger. They are available in adjustable 2-3 piece, and solid one piece. They have powder baskets. You can buy replacement baskets if the baskets that come with your poles are too small, or break. Baskets commonly break with hard use, so if you find a good pair of poles, it’s a good idea to buy an extra pair of baskets for the future.
If you are a shorter person, you can use the light and super-rugged aluminum adjustable 2-3 piece poles for classic skiing technique on the flats. These extend to about 145 cm in the longest models. These will be too short for taller people for good classic ski technique. The reason the back country adjustable poles are so short is because their design is driven by downhill ski technique, which uses significantly shorter poles than flatland cross country ski technique. This is understandable, since pole planting when going downhill would rip your arm off and/or impale you with long cross country poles. However since I am quite short, I can get away with one of the finest adjustable, lightweight but super-strong poles: the Black Diamond Flick-Lock 2-piece pole, which adjusts to 145 cm, which I use at lengths of 135-140. http://www.bdel.com/
No company makes a longer adjustable pole, so taller people are stuck with having to find a long fixed length pole. Ironically, most back country ski manufacturers don’t make one, since again, they are making skis for downhill pole planting technique, not cross country classic skiing. Tall folks will need to research a recreational sport/track skiing pole that is the strongest you can find, and fit it with powder baskets.
I recommend only aluminum poles for back country trekking. An aluminum pole will bend or break, but not shatter and splinter. If an aluminum pole breaks or bends, you can saw it in half with your multitool, and insert a stick, then tape it or wire it up for an internal splint. Repairing a shattered fibreglass pole could get messy. Of course, the bush is full of trees and shrubs, so as long as you have a cutting tool, you can always fashion a rough pole from the bush to get you through.