Hi Geosteel, can't say I've encountered the problems you are having. I've attached a picture below which shows the specs of the pedal, the input impedance is 2m ohms, that seems to me like a good match for the pickup impedance where the high impedance is not loading the pickup.
I do have a high impedance input buffer cct built into my steel but I can switch it in and out, with it in the tone is a bit brighter than bypassing but never had any problems with either setting.
I've read some stuff about the pedal on the US forum, not wanting to blacken anybodies name but Keith Hilton put up a post which in my view was designed to steer US players away from the Lehle and to buy his pedal. In it he made an appeal to buy US and indicated that the Lehle was German made and made references to WW2 as to why people shouldn't buy German products.
He also claimed that Lehle copied his design, almost to the point where Lehle could have taken a lawsuit out against him. I have repaired a Hilton Pedal and looked at the circuit etc in the Lehle and there are nothing alike other than they don't use a pot to control the volume. Hilton use an optical system, Lehle uses a magnetic system.
I believe there is a gain control in the Lehle which alters the way the pedal responds, have you tried adjusting that to see if it makes a difference?