Regarding the convergent curve, it doesn't generally seem to be very popular. I've never looked into it much myself (i.e. read the code), but the justification for it always seemed weak.
Anyways, when we look into changing the window code, I'd already planned to also investigate the convergent curve and potentially dropping it. It was very briefly discussed in the comments when I talked about HF25 plans (or at least I thought it was).