I have not imported yet, but will be soon. This is not a decision I have taken lightly, and have been researching for over a year. It is important to know the possible consequences of using a foreign seat.
Foreign seats are not legal to use in the States. Research your state's laws to find out what legal issues you could have. Laws and fines vary by state. My state specifically states that a car seat violation cannot be considered neglect, but that may not be the case for other states. Use of a foreign seat could also possibly be an issue for your insurance company (or whatever company you may have to deal with if you have an accident). At the very least, they may not pay to replace the seat after an accident, worst case scenario they deny the entire claim. There are many US seats that will keep your child RF for a long time, and I would not recommend going against legal restrictions until there are no other viable legal options to keep your child RF. I have upgraded my son's seat to keep him RF, and there is currently no other US seat that will keep him RF longer than his SKR XTSL (I upgraded from a True Fit because of his weight). If another US seat were to come out before he hits the RF limit of his current seat, I would likely purchase that before resorting to importing.
Installation can be quite different and somewhat complicated for a Swedish seat (dual tethers, foot props, different rules, etc), and you may not find a CPST who will assist you. If you take a foreign seat to a seat check event, they most likely will not help install it and may even attempt to confiscate it. Even a Swedish car seat is not safe if improperly installed, so I would absolutely not recommend importing unless you are sure you can correctly install it yourself.
Importing a Swedish seat would be expensive. 55 lb RF seats start at about $400, shipping is about $115. Figuring out which seat will work best can be difficult, and if you pick wrong, it could be a very pricey error.