I made an online purchase of a 2-pair Sportube years ago but they shipped me the 3 pair. Someone above mentioned the extendability of it. I don't have nor have ever used at 1 or 2 but I concur that the 3 doesn't extend very far. Fine for me and My Better Two-Thirds but if you are very tall and/or ride long skis, it might not work for you. For example, to my wife's great disappointment, we can't put her cross-country skis in there - just not long enough.
You do need to pack out the space between the pairs of skis. Easy to do and useful for all kinds of stuff but watch out for weight. Never tried boots since you have to check any sort of ski bag. That said, I don't think they'd fit unless they were children's although we do put MBTT's cross-country boots in there. I like the Sportube fine, no real issues with it but I probably won't replace it if it ever wears out. I only use it for flying trips and even then only when MBTT is with and I need to haul 2 pairs of skis. Otherwise I just use a 1 pair soft bag for myself The tube protects the skis better but skis are pretty tough..
WRT to packing poles, the way you pack the skis for the tube makes it easy to incorporate the poles into the same profile. Heck, you can pack a bunch of stuff into that profile - extra socks and gloves, spare clothing, sneakers, snow boots, whatever. You put the skis tip to tail with bindings in and wrap them with either a nylon strap or, what I use anymore, a velcro strap. The poles just slide in and are held by the strap, one on each side of the ski pair. This makes a VERY strong bundle. Stuff the gaps with whatever you always wished you could bring but never had the room for. You can pack skis in a soft bag the same way, at least a one ski bag. I never tried it for a 2 pair bag, but I can't imagine any reason it wouldn't work.
I have also retrieved a disconnected tube at destination. Now I use a TSA lock with a thin cable rather than the solid bar. That's goes through the holes. I also run a wire wrap through another hole. TSA can snip that easily if they want to and they can open the TSA lock like any other. They seem to manage without screwing it up other than that one time.