Keith, I am answering you inquiry from Australia, so my answer may not be of much value to you, but in my opinion the Agleader is a preety simple, accurate and reliable system to use and I have retro fitted several 2188's and 2166's with the system with no drama's at all. For technical reliability I cannot fault it - we have about 60+ units in the field with no substantial down time. We take units out of headers (combines) and put them straight into our vehicles for doing our smart sampling for soil and nutrients and also run them in cotton pickers. We use the Agleader branded DGPS system and have found no problems with the 4100 series although the 3100's did have a few minor bugs. The 4100 is a lot more compact and useful for us. Hope this helps somehow, and anyone else that has any thoughts on what is the best of the best out there, I'm very interested to know. Regards, John Dale, Queensland Cotton