I have one and love it! after months of heavy use my TDS meter still reads "0"
Now for the membrane....
they use a higher rejection membrane -GE Desal membrane, (even better than Filmtec membrane), it removes 97% to 98% of all chemical, dissolved solids in tap water. so even though it is higher than 75 gpd
it does NOT mess up your DI resin any faster than a slower one.
This membrain removes (even at the higher flow rate), about 98% percent of all TDS out of the water before reaching your DI resin.
You will not have the channeling effect in the horizontal DI chambers cauze, you can open them and refill them back up solid if you get any air space inside. They are also just snapped on the top of the unit.
You could (if you wanted), turn them up almost vertical.
All the filters used on this unit are standard sizes so- that bs about not being able to get replacements is BUNK!
They also have a decent tech support.
The units are made in the USA by Water General and they are a partner with Honeywell.