iPhone 6 x sim

[biggiepk]

Hi guys.

The store is selling cheap iPhone 6 x sim and i don't know what are things that are limited to x sim phone??

What do i lose vs fully factory unlocked phone? What should i worry about?

 

Thanks

[BCConnection]

These are most likely not unlocked Sprint phones. The X sim will probably be limited to H+ speeds if the LTE bands are not unlocked. 
I dont know about the 6 but the Sprint iPhone 5 could be unlocked to work for GSM and HSPA bands only. 
That being said the new iPhone 6/6+ and most likely the 6S/6S+ are pretty much the same phone across CDMA carriers. Which makes them able to pick up ATT and TMobile LTE Bands.