Hej from America!
Haven't tried either bin, but Dennis makes a point about format and weight for some of your activities. If your pockets were as deep as a Dungchen, the ideal combo would be a full sized bin and a midsized "companion". Dennis has some experience with that.
Jerry also makes a point about the SLC-HD having the latest technology whereas the word is that Zeiss plans to introduce new models. Of course, that's probably what's driving the discounts with the FLs, trying to clear their old inventory.
Since both bins offer spectacular views in the center of the field, it will come down to other differences btwn the bins. Here's a sample "Pro" and "Con" list you could make to help you decide.
Focusers. Each focuser has a different "feel" and speed. Which suits you best?
Ergonomics. Which bin will be less fatiguing to hold on an all day outing?
Edge performance. Some FL users have commented on the steep fall off at the edges, which might or might not be an issue for you. If the SLC-HD is similar to the SLC I tried, it has a generous sweet spot and gradual fall off at the edges. If you try them both again, move your target off center to evaluate this difference.
Distortion Levels. FL reviews report a relatively high level of distortion (pincushion). Some people won't notice this, others will experience a "scrolling" effect while panning. If you compare the two bins again, do a lot of panning with them and see if the higher distortion in the FL is noticeable to you.
Viel Glück!
MeisterB