yes it is, there is no difference between them in view of the meaning but it would sound quite different depending on who used it. "맛있옹" is usually used between young lovers and most people feel it makes us get goose bumps, you know what i mean. here are some other examples. 그랬엉? (그랬어/그랬어요) 옹(응) 너무 아팠엉(너무 아팠어), 호~ 해줘 자기야 those are very sweet but can't stop getting goose bumps all over.:)