Hi, MEB. Thanks for the reply. Having tried AD I have to say it looked an awful lot like a replacement for DrawPlus. Most of it I recognised instantly, which is not a bad thing, but highlights the fact that what's important to us users is not how clever the technological tricks are behind the scenes, but what it's like for us to use. As others have already remarked, arrowheads are basic drawing-software-101 stuff from a user's point of view.
There's not much wrong with DrawPlus (well, apart from its tendency to crash now and again and its limited support for some filetypes) but I'm conscious that it's no longer supported. As a long-time Serif customer I'm happy to hand over some more money for new software occasionally if I think that the products I'm getting are moving forward, not backward. Same goes for PagePlus which I also use heavily: I was eagerly awaiting a chance to buy the Affinity "equivalent" (can I use that word?) but now I'm not so sure.
I haven't seen any workarounds that let me do bendy arrows easily and quickly, dozens of times, over and over again (see attached snapshot) but I welcome correction. (Before you say it: no, straight arrow shapes aren't good enough.)