I guess it depends on how big the fare difference is one for one's dates, as I've often priced ScootPlus and SQ econ out as neck-and-neck on this route. For anything other than a big saving, the pros of ScootPlus (it's a great seat, like "Domestic First" in the US, actually preferable for me for short haul) are massively outweighted by the cons of not flying SQ metal in coach as *Gold: forfeiting access to Suvarnabhumi Fast Track as well as several good-to-fantastic lounges serving hot food and champagne (among them SilverKris, a real premium lounge, unlike the *Gold lounge at SIN) as well as 20kg less checked luggage.