The actual point of this thread was to ask How effective is the ADSL Nation modem M3?

On long high attenuation lines it really is a case of try it and see. As others suggest, the 2700 HGV is always a good starting point but how teh M3 will compare, only a test can prove it.

On your line it could fail to sync, but on your neighbours it might give better performance than the 2700.

Well after month's of fiddling, and tweaking and new router's and clear line we have a sync speed of 2692kbps.

To answer the original question the X-Modem M3 has no optimisation to make it deal with poor conditions any better than others on long lines, in fact I would suggest that it wouldn't be a good choice for a line with exceptionally poor conditions as it is a relatively old chipset, so newer chipset based modems would probably deal with a bad line better.