I have a pair, and they work fairly well except that my position isn't ideal for them. The problem I have is that my hands naturally want to hold further than the bars extend, but that's mostly because I ride a small bike with a short stem. If I choke up on the bars my elbows hit my knees.
I keep them on and more or less ride in the "invisible aerobar" position, since I don't actually hold on to the extensions. They make that position much more comfortable so I can stay in it for a long time, and they keep my arms narrower.

That being said, I prefer longer aerobars and would replace them if it was free. (which also means the shorty bars are good enough that I'm not willing to spend the bit of money)
If you think you might be fine with the short ones, your best bet might be to buy a brand which allows changing the extensions.
If I was in your position, I'd ride around in the invisible aerobar position for a bit and see where your hands naturally want to be, and decide if the shorty bars would be too short.