As posted in the Tevion LCD thread:
Well I've never seen the Keene converter in action so can't really say how well it works. But at half the price of the JS-Tech converter it must have compromises in performance.
At the end of the day you are trying to improve on what the RGB scart input on your LCD offers and therefore I assume that the PQ is important to you, therefore I'm afraid the advise is to buy the best converter you can and IMO that is the JS-Tech one! If you do go with the Keene converter and don't like the quality then you will need to buy the JS-Tech one and sell on the Keene at a loss, therefore it will have cost more money. But if the Keene is good enough for you you will have saved a fair bit. Decisions, decisions. This hobby is never easy but always far from cheap!
Mark.