I have had it for 6 mths and love it. It is so much cleaner, just vac the surface.
I really love argonite but it's more $ than Home Depot etc sand. It is lighter and doesn't compact or get layers. I do put my vac all that way in it and pull it out, some goes in the drain but not much.
As for washing it in the winter, that's the hard part. I did it in the sink and I hope I didn't mess the kitchen pipes up! Little bits at a time works best.
I haven't had any problems with my HOB filters in the sand or in the argonite sand. I had sponges on the filter intakes but took them off. If I stir the sand I shut the filters off but only for about a minute.