To be frankly honest I think you are a bit on the wrong track here. I really do not see how your coverage between LTE and 3G has anything to do with this problem. Here in Norway our 4G network works on a frequency band which the new Ipad does not support , therefore it does not even try to connect to LTE, but still get this problem when switching between Wi-FI to 3G and to Edge and so does people all over the world.
To say that this problem is caused by a carrier problem is like saying that "The World should evolve around the New Ipad ". Keep in mind that 3G is a standard that have been around for a long time and all manufacturers that produce 3G devices in any kind of form make their devices to be compatible with this standard, NOT THE OTHER WAY AROUND. Just imagine the chaos this would create. Makes sense right?
To make it clear to everyone that still does not seem to understand the basic thing here.
Whenever a new mobile internet device is release on the market there is no dialog or meeting between the carriers and the manufacturer (aka. Apple) of the device on how they should make the carrier service suit the device needs, it is the other way around folks. Just like in this case Apple is responsible for making the Ipad, phone..etc be compatible with the 3G/4G protocol/standard. 3G works great on all previous apple devices, and there is no reason why 3G connectivity should be adapted in another way on the new ipad just because the device also supports LTE, the problem seems to be how the new Ipad chooses/switches between the different bands, hence it is either a software problem, or a chipset problem. Either way, Apple is responsible for this issue.