I had an offset. 400lbs, 36 x 20 pit and a 20x20x20 firebox. It was a real job like a fireman on a steam locomotive. I had it for about a dozen years. It got used less and less, usually only when I had a catering job I couldn't get out of for a friend. Then I got a RecTeq RT-700 and it never breathed fire again. An enthusiastic young man came and picked it up and gave me $200 for it this year.
I do think the E6 or S6 will give you the flex you want. It's ready to do what you want right out of the box. I'm sure the Hasty Bake is as well. They have a rep that's pretty much cult-like. Both are well above the cost of what you posted.
If small is what you want, an 18" komado is really flexible. I have a 18" steel komado (Big Steel Keg/Bubba Keg that is great for 2 people for 95% of the time.
But if $500 is your range, I'd get a 26" and a Slow n Sear.