A line with 50dB attenuation will unfortunately show limited sync-speed improvement from ADSL2+ compared with ADSL1, perhaps 300kbps, though that is worth having. The Internode plot on
this page illustrates the position. Kitz's calculator
here provides some numbers.
With regard to interleaving, at these levels I doubt it would significantly affect sync speed, more the speed of actual data transfer. In fact that might be better with interleaving on because fewer uncorrectable transmission errors result. With interleaving off all errors require packets to be retransmitted to correct them, effectively reducing the rate at which useful data is transmitted.
Interleaving has a more significant effect on latency, and gamers are usually keen to have it turned off, even at the expense of some line instability (disconnections). Unless you are a serious gamer I suggest leaving it on is probably the better option for you.
In any case to avoid confusing the DLM it is best not to tinker with the setting during your training period. Post training the experience of others on ADSL2+ has been that the 21CN DLM can be quite aggressive and leaving it to sort itself out is often the best approach.
Opinions, not facts but I hope you find the comments useful.
David
