I asked Patagonia when I saw that the Ready Mix was off the website- they said it was part of their spring line and would be back for that season. Incidently, the Ascentionist appears to be a heavy-duty Ready Mix, and I seriously want one for ice climbing (Rock and Snow has them if you want to try one on). Note that my RM has some abrasion damage from normal use with a pack (from the sternum strap) and where the velcro rubs the fabric on the wrists. I have also experienced this with Schoeller Dynamic.
If you don't need the hood, check Ebay and such for the Patagonia Figure 4- same fabric as used in the reinforeced parts of the Ready Mix, weighs under one pound, and is durable. They go for pretty cheap.
Edit: I notice that we travel in the same areas for winter (cats and Dacks). For me, it is a toss up whether I take my Ready Mix or my Schoeller Dryskin Extreme jacket on backcountry trips in those areas. The RM is the perfect all around shell- dries fast, blocks wind, good features, decent breathability. The Schoeller fits better, moves better and is more breathable, but blocks less wind and water. If I could only have one, it would be the Ready Mix, but when snowshoeing up hill on the straight-up trails in the Cats/Dacks with a winter pack stuffed for three days, the Schoeller is really nice for moisture control. This is where Powershield fails for me- my back is soaked in sweat no matter what the temperature or my baselayer.
If I am going to be above treeline much I take the RM for the wind protection- otherwise I often opt for the Schoeller Dryskin (dont like dynamic) for the fit/breathability.
Last note: as much as I like Schoeller Dryskin, I would not buy a shell made from it again. It is too pricey and heavy- Patagonia, Cloudveil (Inertia) and Mountain Hardwear all have similar fabrics that cost much less. Look for any stretch-woven lacking a membrane.
Edit again: If you are ever in Delaware Water Gap, PA and want to see a Ready Mix, Schoeller Dryskin jacket, Figure 4, Gamma MX, Essenshell, and some other softshells, let me know.