Haven't been able to try with the NTE-2005 but I just tried with an old ADSL filter into the test socket and my attainable was worse than the MK3.
I was surprised it made such a difference, even if the ADSL filter does have an inch of flat cable. (I bet its not twisted pair)
Generic ADSL Filter: 94816 down 31959 up
Openreach MK3: 95290 down 32318 up
Granted my drop wipe is blowing around like a chinese lantern right now.
But the MK3 attainable was around the same before and after the swap. I had expected if anything for the generic filter to be higher as its unlikely it has anything filtering the DSL side.
I was hoping to use the adapter from the Dreamcast that converts RJ11 directly to BT plug, thus not having any filter at all. Alas, I can't find the darn thing.