Well, I've had a few weeks to test out my Boomerang putting practice aid. To be quite honest I don't have enough long straight paths in my little house to roll out the artificial grass mat to its full length so I only really use it to practise 4-6 foot putts. That's really the only thing I wanted out of this device and it works PERFECTLY. The actual device consists of the aforementioned grass mat (apparently running at the same Stimpmeter reading as Carnoustie during the British Open) and a ramp that you can incline at a number of different angles. There is a cup that sits at the top of the ramp, the depth of which is adjustable. The whole system is designed to help you judge pace... but as I say I really only use it to practise short putting.
With this device I've found exactly what I've been looking for. I can roll out the mat for a half hour in the evening and just hit tens or hundreds of putts thus straightening out my stroke. Having been very busy and also with the inclement weather I haven't played any golf in the last month... so I don't know if I'm putting better. But I think my putting stroke is improving.