The title says it all.
While anchors speed up construction process, you can't use preview without generating glyphs.
I haven't tried it myself, but Glyphs is reported to have a much improved system for building accented glyphs. I'd love to try it, but I work on a PC.
You can preview the placement of diacritics on base glyphs in the previwe panel by using the Anchors tab. It is not very comfortable but it works...
Yes, but I had Text or OT tabs in mind.
Thanks Eigi, I'd never noticed the anchors tab!
It is not one or the other. Anchors are tool to create composites quickly and consistently. When you have many diacritics positioned above/below certain character then use anchors. They are not very useful for positioning when only one accent is being placed and/or when the result needs to be decomposed and merged (e.g. aogonek, eogonek).
Nevertheless, if you find achors too confusing, just use composites. It is not such a big deal.
Note that anchors are not MM-compatible, that is their positions do not interpolate. You can fix that with some macros though. … or you can generate composites before interpolation.
Also, consider looking FLS manual for alias.dat. That can speed your process up a bit more.
But how do you check problematic kerning pairs for accented glyphs created with anchors?