This topic comes up on a fairly regular basis, so you can take a peek at previous threads just by searching 'Rio Grande Valley' or "RGV".
I'm NBT (native born Texan), & I have lived/worked in most areas of the state. That being said, there culture in So TX is very different. Predominately Latino, much poorer & less educated than other areas in Tx. The southern end of RGV is a tourist mecca and winter 'home' to retirees from colder climates. But if you travel much more north than McAllen, the geography is not so pretty, the climate is harsh and the economy much more 'agrarian'. If you couple this with the fact that Mexico is experiencing severe unrest & periodic episodes of fairly dramatic violence related to ongoing conflict among drug cartels. . . newcomers may find it too different from what they are used to.
Hospitals reflect the culture of the environment in which they are situated. If you are a typical American, it is a rude shock to find yourself part of a minority - unable to speak the dominant language or fit in with everyone else. If you are not bilingual, it will be a distinct disadvantage. Anglo/Yankee 'Migrants' are perceived as temporary - to make enough money to move back where they actually want to live - and treated as such. Based on my own knowledge, healthcare in this area remains very physician-dominated. Medicare/Medicaid costs are the highest in the nation (yep) due to physician practice patterns and absolute loyalty of their unquestioning patients.
Just remember, no employer is going to offer any more $ than they absolutely have to. So, if you find an employer willing to offer much higher salaries, bonuses, relocation, etc . . . it's not because they are generous benefactors.