First off,
I'm the one who mapped the Sensorly blips on 26/217. Each time, I was connected to LTE according to a the signal apps I use and my phone's LTE Engineering screen. The problem with these signals is that they are very weak (probably from a site fairly far away). We haven't nailed down which tower(s) those signals are coming from, as many sites in the area are being worked on. Tualatin has a site that was accepted by Sprint as 4G complete and is currently broadcasting LTE.
EDIT: Just realized that I goofed...the accepted site is in Tigard (off Durham Rd.), not Tualatin.
This is an S4GRU policy. This site is not affiliated with Sprint in any way.
Can't say much on this, except that the data comes directly from Sprint (which is about all I know anyway) and is highly accurate. I do recommend becoming a Sponsor, as there is a ton more information available in the Sponsor section.