Sierra Wireless Compass 885 HSUPA 3G modem
aka the O2 Business Modem
As a USB modem, the 885 worked impeccably. We tried it out on both T-Mobile's network and on Vodafone's, in central London and elsewhere in the capital where we were able to tap into the network's HSDPA link - rated at 7.2Mb/s, according to Windows, though rather less than that in real-world testing. From slotting in the modem to being presented with a usable connection took a fraction over 37s - slightly slower than the 33s it took to perform the same task, on the same network and in the same location with the Ovation MC950D.
The T-Mobile connection wasn't particularly rapid - the Vodafone was better - but we got almost identical throughput readings with the MC950D, so this was clearly a network factor rather than the hardware. Indeed, the 885 performed much like the Novatel product. Both are based on Qualcomm chip technology, which may explain why.
One thing we did notice with the 885: it doesn't get as hot as the Novatel Wireless product. Both were evenly matched on the signal strength they registered, and while we'd have liked to see more than 2-3 signal bars lit, we had not trouble with either modems' performance.
O2's offering the 885 as the Business Modem
O2 is offering the 885 for free on monthly tariffs ranging from £53 to £143 including VAT, provided you sign up for 18 months. Or you can have it on a one-month contract ranging from £41-143 if you're willing to pay £98 for the modem. If you choose any of these, beware: the O2-sold modem is locked to the network.
If you want the freedom to move from network to network, the unlocked 885 is priced at around £150. That's £10 less than the MC950D is currently going for. The MC950D is a good modem, but the 885 is no worse and a tenner cheaper.
That said, if you're going to be switching SIMs frequently, it's much easier to do so with the Novatel Wireless product than the Sierra one, and we'd personally pay the £10 for the convenience. The MC950D is also compatible with Linux, while the 885 is not, and that may affect your decision which to buy, too.
The merits of an on-board Micro SD slot are entirely subjective, but everyone can agree that a good USB 3G modem needs a decent array of connectivity options and a solid signal-sniffing ability. Sierra Wireless' Compass 885 has both, and it's let down only by an unnecessarily fiddly SIM slot.