Craig,
As I mentioned earlier an exhaustive set of controlled tests were performed and reported
here.
Although there was much postulation, and this ramping was shown to occur irrespective of user load, there was no conclusion as to cause. Turning firewall off, turning wireless off all reduced latency. But the matter was not resolved.
Ravenstar's SH2 did not display this ramping, and my SH1 never did either.
So now to further speculation taking into account what QTX has just said. In the SH2 trial, Ravenstar's SH2 suffered from the BSR incompatibility issue associated with BPI/TEK. I don't know if TH at Crawley is on a Motorola BSR and what Craig#s CMTS is. But if it is a BSR and we can chase all the other users who have reported the ramping and get the question reopened.