Bill
I just got the mifi a little over a month ago. Been stationary at the time being here in Gulf Shores AL. Its worked good for this area but it should as its close to big cities. I bought the sleek from the 3G Store and adapter for my Wilson external antenna. I can't really give you any results for the sleek yet as there has been no need for it here. Also 3 Gig of use seems like a lot but its marginal at best. If you do any web surfing for any length of time it eats up time like crazy. Also the more used web sites have a lot of graphics on them recently and they are helping to use up your time. Last summer I was getting by with 3 to 4 Gig easy. The last couple months I have been up to 10G. Mind you there are two of us using this at the same time quite a bit.
If I was to do this again, I would go to Mellenicom for $59.95 a month and get 20G of time per mo. Thats a bargain and people using it say its as good as anything else out there. Just take your time and look into your options. Another place to look into this with a person that is in the know is Jack Mayer on Escapees forum. He has a Web site here
http://jackdanmayer.com/communication.htm
On reading this again I should also say that I am with Verizon and now get 10G per month use for a hefty proce of $79.95. To get the 10G you must go with the mifi.
Dave