If you've got a rooted phone, you might try toggling the CDMA bands (class 1 is 1900 and class 10 is 1x800) in a app like network signal guru to see if one or the other is better for you. Some phones also have this ability through the data menu, but my experience with that method was nearly disastrous. The phone I tried toggling BC 10 on got stuck in a boot loop. The only way I could stop it was airplane mode as soon as it booted into android (before the radio became active) and reenabling BC 10.
I hope it is. The E4 + I'm using doesn't seem to do any B25 CA while my essential did with two 5x5 carriers. When I first connected to the 10x10 carrier yesterday I ran a speed test and the results were 5mbps on the download.