Tasdoc said..
I used to have Retros in 5.5 and 6.5, used both on a Sumo RDM mast. Circa 2015 version. Used for a few years, quite liked it but ended up switching to NCXs as they feel more stable overpowered. Now I miss the bottom end grunt of the Retros...
Thanks for the reassurance!
I went ahead and ordered a 7.5 + 460 Sumo, based partly on this comment. I bet it will feel a little soft, but I don't weigh much.
5.0 & 6.0 on a 430 will follow once I put aside more $$$

Very much looking forward to those.
Hoping the Retro is stable enough for my use case. I hear great things. My first and only sail for years was a 1994 Sailworks 3-cam Syncro @ 6.5. Very stable platform. I didn't realize stability was a thing until I started sailing on Severne Gators a few years ago and kept losing control as their draft moved back in big gusts. Terrible feeling.
I have to wonder if your RDM Sumo contributed to some of that low-end power you're talking about...The camber of the sail could be fuller/deeper than with SDM since the luff sleeve has less mast taking up space in there.
Thanks again