I think that you shouldn´t be allowed to write in competitors sales threads if you sell a similar product or promote one in your donor sig even if you actually buy your competitors product. The reason is pretty simple. Your "review" will of course be biased and any support questions you might have doesn´t belong in a sales thread anyway. Hence, you really doesn´t belong there since you will not contribute with any unbiased or useful info - all you do is to indirectly promote your own product or bash down on your competitor on their expense in their own sales thread and I don´t think that´s fair. Any thoughts?