BarTender: Johnr but the telecom xt device also supports 900mhz too.
I also tried my vodafone novatel 870, however that was equally unreliable.
The problem with the hsdpa / 3g transition is that if you are in a patchey area the modem can spend all it's time doing the transition and never give you a solid connection. Which is just as useful as having no call at all.
I'll give it another go today and see how it goes...
MF626 only does 850MHz WCDMA, it doesn't do 900 WCDMA only 900 GSM.
Signal strength shouldn't make too much difference in the CELL_FACH / CELL_DCH handovers, it's something that just occurs automatically if you're not transferring data.