All 5 of my most local sites in Bedford are showing 15MHz in field test mode. Only on the Upload section though, Download always shows unknown, I assume this is because field test mode isn't updated by Apple.
Funnily enough, it hasn't helped congestion in the slightest. I'm getting the same speeds at the same times. During rush hour, 4G speeds get down to 1mbps down and 10mbps up standing right next to one site in particular. Other sites, congestion isn't as bad, with speeds of around 5-15mbps at peak times.
These are all MBNL sites, and EE will be getting 20mbps+ while Three is at 1mbps from the exact same site at the same time. EE do have more sites not in the MBNL share here, plenty of legacy Orange sites that are still functional, at least one is Orange/Voda that EE have been out to and upgraded to 2G/4G.
There was a point a few months back where this particular congested site couldn't even take calls or texts during peak times when my EE phone connected to the same site functioned perfectly fine. It doesn't have antennas capable of 800MHz, I can only imagine if they gave it 800MHz it would be completely unusable @ 5mhz.
I've seen absolutely no movement in legacy Orange sites being integrated into MBNL around here, but the large majority of them are still active. The Orange fallback no longer exists (it shows in network searches but cannot be connected to) except one particular site in the town centre where coverage from the local 4G MBNL site is awful and anytime you enter a shop you will roam onto Orange.
EE users get Orange 3G, Three users get Orange GSM calls/texts. Seriously, if they shut this sites roaming off, anyone in Bedford town centre on Three who entered almost any building would have no service. It's been this way for many years, they probably have left just that one site on for fallback as it must have huge amounts of people roaming on it on a daily basis.