I have used hl970s for cycling for a few years now with mixed results.
Pros: They look good, are super bright and can be run off 12V battery. Easy to interface with rs232 or 485. Very nice scrolling text mode, and jitter-free 0.1s updates.
Cons: Limited character set (as supplied), confusing documentation, requires a control box and cabling, large text is extremely ugly, and when powered by mains they will interfere with magnetic transponders (mylaps and tag heuer). I struggled to get anything out of the supplied software and in the end replaced it with my own.
Overall I'm happy with them, but it took a manual hack on the firmware to fix the character set for my use, and I had to write my own image generator for a usable vertical mode.
The only real problem I have has with them is that the LEDs are soldered by leads and rest on a plastic screen. This plastic screen tends to impact the LED shells causing cracking. This litters the inside of the case with small fragments of LED (see attached). So far, none of the LEDs have failed.
They will not talk Alge, so support is pretty limited in other software. I guess it dependson the tool you plan to use - sorry if that is no help.