There is zero advantage of being in Global or LTE/CDMA mode when connected to the Sprint network. Anyone who claims...OMG I get better LTE signal in Global mode vs. LTE/CDMA mode is just a placebo effect. As we know that measuring a LTE or CDMA signal is pretty tough given how dynamic it fluctuates every second. All switching between Global and LTE/CDMA mode does is just force a rescan of the frequencies which maybe a rescan of frequencies finally gives you the LTE signal especially if you are in a weak cell edge LTE area. If you are in a strong LTE area, you can try swapping between Global and LTE/CDMA mode and you will find it makes zero difference.
All Global mode means is that you can use the GSM/HSPA bands when you are travelling internationally but that does not help with gaining a Sprint LTE signal at all.
FWIW, I put my phone in LTE/CDMA mode on my G2 and I don't have problems connecting to LTE.