[Samsung Galaxy S9+ Questions & Answers] scottusa2008:
Carriers have pro's and con's... If you are worried about having high roaming use then perhaps pick up an unlocked phone that will work on a different provider (with applicable plan through the provider) and use it as a mobile hotspot. Then connect your S9+ to the mobile hotspot and you should be ok.

TBH one of the things you should consider when your buying service through a carrier is the coverage the carrier provides as well as if/what limitations may exist. In your case if you roam a lot and the price of roaming is to much then perhaps consider a different provider when your contract is up.

The phone is carrier/network locked which means it can only be used on the carrier you got it from. Because the phone is carrier locked you can not use any other sim card other then what is provided by the carrier.

Nope

To be honest you just gave 2 pro's and only 1 con over the device, which would kinda answer your question for you... But again that is the kind of question only you can answer..

IMHO if your sole purpose on having that phone is that you must have it rooted, then this phone is not the one for you. If your only trying to root the phone so you can get cheaper roaming data by using other sim cards then you probably shouldn't be trying to root the phone anyways (not that root is even possible cuz it's not... It's just better to get it carrier/network unlocked by paying it off).

On the other hand for the most part even if it was possible the device could be rooted it won't give you much outside of what you already have. Granted I have had phone(s) being samsung and other where rooting the device allowed me to get better performance and battery life. With this phone it is the first Samsung I have had that is quite snappy, battery life is surprisingly good and overall it works quite well with just the stock firmware.

About the only thing I would root the phone for (if it were possible, it's not obviously) is for nandroid backups. Still even from factory data reset to back up and running doesn't take that long anymore. Outside of that I myself have no reason to root the phone.

I would strongly suggest you entertain/consider those notions after you paid the phone off. But just as an FYI once you get the phone unlocked (after paying it off) you can use it on T-Moble, Sprint, Verizon, AT&T... The G965U and G965U1 whether bought from samsung or the carriers themselves have the same internal hardware. The software determines what bands and carrier compatible features are active... Should be noted that carriers may have additional requirements (like AT&T not letting non AT&T S9+ use VoLTE) for specific services/features.

So if anything pay the phone off faster so you can get it carrier/network unlocked.. The phone or the fact the model isn't rootable isn't the real problem here, it's the data roaming charges your carrier has.

Keep the phone and use it until it's paid off.. Then get it carrier/network unlocked would be my suggestion. At that point you can use a sim card with a different provider for cheaper data roaming.. Or after it's paid off and network unlocked you can just sell it (you could probably get more for it since it would be unlocked to work for any carrier).