Newt yeah sort of, its probably a compatibility issue, broadcom is probably the biggest name in the xDSL industry, I expect when modems are introduced to market, if they get tested then its much more likely against broadcom dslams than lantiq dslams. Sky's g.inp ADSL I believe uses broadcom dslams (not entirely sure tho), which means broadcom have a lot of technical experience with the technology.
Back in my ukonline days using connexant dslams, the dslams were configured to be more capable than BT wholesale's dslams, by supporting SRA, and it was amazing when it worked, but compatibility was a dog compared to broadcom. SRA itself only worked on older gen connexant modems, and without SRA overall reliability and performance was inferior to broadcom.
The hauwei deployment is not problem free, but rather they have managed to get automated workarounds in place to get problems down to an acceptable level for support costs.