I'm a radiofrequency engineer by training and am involved in the RF power amplifier community (our company delivers WiMAX PAs), so I was very interested in getting away from FiOS and on to Clear.
I live nearly equidistant from two Clear towers in NW suburban Portland, 0.7mi and 0.45mi from the towers. I initially took two subscriptions to Clear so I could run both simultaneously and determine which tower would give me better service.
The answer was neither. Two Motorola modems, two placements in windows on second floor of house, no difference in performance. After trying all kinds of "home remedies" to improve modem performance, I recently swapped out a Motorola CPE 25150 for a new Series G modem by Gemtek.
I had an interesting learning from all this effort that I think is worth sharing with the Clear community. In the modem location where the Motorola modem has its best performance (1-3 lights using the tower east of house, 0.7mi away), the Series G modem now gives 4-5 lights. However, in the best location for the west tower (0.45mi away through dense suburban trees and houses), the Motorola modem gives 1-2 lights while the Series G modem gives only 1 light. I tested this in another location in the house where Clear signal is weak, again the Motorola modem outperformed the Series M modem.
For me, the most surprising part was the significant improvement between the Series M modem and the Motorola modem in the location with best line-of-sight to the eastern tower.
I will also say that, after running two Motorola modems from different antennas, in weak signal conditions it improves speed to reset the modem daily. You can do this by typing 192.168.15.1 into your web browser while connected to the modem. After logging in with password "motorola", you can reset the modem by clicking the starbright logo in the lower left corner of the information display. I have noticed that weak variable signal conditions seem to cause the modem to, using a very non-technical term, "block up" and degrade in performance. I've seen a reset take 0.5-0.75 Mbps performance up to 1.5-2 Mbps with the same RF signal power level.
It's time for Clear to start shipping indoor modems with external antenna compatibility. A very simple external antenna will outperform the slot antennas built into the modem circuit board and be less sensitive to the physical orientation of the modem.