Hi jeter,
Did the signal issues start recently or have you always had them? Do I recall correctly that you just received a replacement device? I am just wondering because your question coincides with the service /slow speeds reported with the 50580 PRL. When setting up the new device for you the Sprint rep may have applied that PRL. Sprint has just reverted back to 21081 so you may give that one a try by going through the same steps you did above. You didn't say what the PRL was before you updated but your speeds would have most likely been worse after doing the update when you did. This may improve your situation... Just another option!
If the PRL and profile updates do not help, politely but persistently contact Retentions and explain that you really would like to stay with Sprint but your speeds and reception just are not sufficient. When you are almost at the end of the 30 days, tell them that you are just going to have to switch carriers and since you will have a documented history they will most likely give you an Airrave. I have seen quite a few success stories on the forums. If, by chance Retentions will not help near the end of the 30 days then perhaps another carrier with better coverage in your area may be your best bet.
Good luck