" So is the consensus the MK2 plate is better than a run-it xte-2005 for keeping out RF on adsl2+? Or would I maybe be better to do xte-2005 + RF3? "
From your point of view you probably need something like that which attenuates even mode pickup on the overhead wires. The modem should have some rejection of it's own but manufacturers are coy about giving figures !
As to which is better, suggest you need at least week long test with each to decide which is best. ( In my case if the speed is going to drop it is nearly always on a sunday evening, but on average only 1 week in 3. I just check on monday and if necessarily switch the modem off for 5 secs and swear - most important !)
Now off topic :=
The RF3 etc aren't supposed to be bandpass filters, they are common mode rejectors, BUT because of the limitations of magnetic cores etc each wire has some leakage inductance which doesn't couple with the other winding. The effect of this is a low-pass filter which limits the bandwidth ( REAL bandwidth in Hz!) So the design inductance has to be limited, which curtails the low end useful frequency in order to get a desired high frequency performance. (I understand the RF2, aimed at telephones ? had to be scaled down for ADSL as the RF3)
VDSL has an enormous frequency range , about 608:1 as against 38 for ADSL1 & 2 and 76 for ADSL2. 200:1 is a more comfortable design range.
So I suspect a VDSL common mode filter is a compromise - either sacrificing high end performance "The S/N is usually poor anyway at that end so no loss" OR low end " The high end is more susceptible pick up and low frequency interference comes in via power supply anyway". Measured performance would be useful.