Yarn substitution help

I’m looking to knit the Mommy Snug from the summer 2006 Interweave Knits. I haven’t ever knit an adult garment before, and don’t really have any experience knitting with cottons. The pattern calls for Gedifra Cotton Merino (50/50 cotton/wool) that I’ve heard is anywhere from a DK to aran weight. I’ve found Classic Elite Four Seasons Cotton (70 cotton/30 wool) which is somewhere in the worsted/aran range.

Gauge for the Gedifra is 17st/4" on US 9s. Gauge for the Classic Elite is 18st/4" on US 8s. The pattern designer seems to think the Gedifra guage is a bit too loose, and she prefers it on 8s.

Any thoughts on whether this would be a good substitute or whether any other yarns might work better? Or even what to look for when trying to find a subsitute?

I don’t want the finished sweater to be too heavy, and I’m hoping to wear it in the summer and fall, if that helps at all.

It’s hard to say if a substitute will work or not, but since the content of the yarns is similar and the gauge is so close, I imagine that the Classic Elite would work. If you’re able to get one ball of it to try it out, you could swatch and see if you could get the gauge specified in the pattern and if the resulting fabric looks good. Make sure to wash your swatch too to see if it changes at all.

Hope that’s somewhat helpful–good luck!