Not sure who's website you're speaking off (perhaps Avon Grips) because Crampbuster and Throttle Rocker are two different companies. That being said, yes I looked at both. I went with the Crampbuster CB4 (I think) because it has the right side offset. Both items are very similar. A friend was buying one months ago and a customer at the Harley dealership told him the rubber friction TRs work better than the velcro TRs. A right side offset (called the TR Left Side) is only available in velcro from Throttle Rocker, and only friction hold from Crampbuster.
They are so incredibly similar that I don't think you can go wrong with either. Just pick what you think will work best. I wanted to push mine as far to the grip end as possible.