I installed my GXP7L7B in April 2016 as a replacement for a SteppIR DB18E which had become a maintenance headache. I am very happy I made the switch. The GXP has proven to be trouble free and performs extremely well on all covered bands (40 through 10 meters).
I have been a Ham for more than 60 years and remain quite active DXing and contesting on a regular basis. I needed antennas covering all the HF bands including WARC bands but, since I live on a typical small city lot, I do not have room for multiple towers or multiple wire antennas. I installed a medium duty US Tower TX455 crank up tower and, initially, the SteppIR DB18E which covers 40 through 6 Meters and seemed to be a really good solution... until maintenance became unbearable. There aren't many solutions out there that I am aware of that will allow coverage of 40 through 10 meters with directivity and good gain on all these bands AND will not overload my TX455 crank up tower. I am delighted to have found the GXP7L7B (7 elements, 7 bands) which accomplishes just that. And, NO MOTORS OR OTHER MECHANICAL MOVING PARTS ;) I did have to add an Innov 5 element LFA yagi for 6M above the GXP7L7B but it is very lightweight, minimal wind loading and runs rings around the SteppIR DB18E on 6M.
Manufacturing quality is superb with tight tolerances and first rate quality of all parts, including all stainless steel hardware. During assembly every predrilled hole lined up perfectly, every single part (and there are a lot of them!) was included, and the specified dimensions were 100% correct.
The GXP7L7B is a pretty big antenna but it does clear my property line in the back yard. Assembling such a big antenna presented a dilemma - where to assemble it and how to get it up on the tower. It turned out to be relatively easy. I assembled each of the elements and the boom separately and laid each of them on a couple of saw horses. Then, using a small man lift (which just fit through my back yard gate), I installed the boom, sans elements, on the mast, then rotated the boom as necessary and raised each element, one at a time, up to the boom and bolted it in place. Worked like a charm :)
The GXP7L7B has a big advantage over the SteppIR when it comes to rapid band changes - no need to wait for the elements to move into place. This is extremely beneficial in contests that have separate multipliers on each band since an important strategy is to move a station to another band to obtain another multiplier. This requires QSYing in seconds. Instantaneous band changes are no problem with the GXP7L7B. In addition, SO2R (Single Operator, Two Radios) is also facilitated with the GXP7L7B since it has a separate feedline for 40 meters. I did add a DX Engineering RR8B-HP 8-Port remote antenna switch at the base of the tower and an Array Solutions BandMaster III Universal Band Decoder to allow rapid and effortless band changes between the multiple GXP7L7B feedlines (40M, 30M and 20-10M), the Innov 6M yagi, and an 80M Vee wire antenna.
Performance of the GXP7L7B has been outstanding. With three elements on 10 through 20 meters, as well as two elements each on 30 and 40 meters, I work DX easily and do quite well in contests. It is at least as effective as the SteppIR, which, frankly, was quite good - when it worked.
The GXP7L7B was engineered to endure harsh northern European winters and it has held up well through numerous storms here on the West Coast. No damage to any of the elements or other antenna components through several severe wind storms. SWR is very good with decent bandwidth on all bands.
In summary, I am very happy with the GXP7L7B and definitely recommend it.