I really don't love this move. Ignoring the Gawn aspect, who I'm big on fwiw, I just feel like you're taking the best forward prospect so that you can pick a forward over a ruck, essentially, and given English/Marshall at the top (far, far better picks than any forward) or Xerri/Grundy (far better value than any comparable forward) are all in the rucks it feels like a wasted opportunity.
As well as the factor that Jackson as a forward provides incredible cover to Gawn/Grundy through their byes or just if out for a week for whatever reason (cover applies to all rucks really) and it just feels like Jackson at F1.
Really only case for it, imo, is you don't like any of the Gawn, Grundy, English, Xerri or Marshall (or another) group to pick them ahead of the likes of Heeney/Flanders/Macrae?
Maybe I've got a different read but if you asked me to name the position I feel the most certainty with the premiums it would be the rucks. English might actually be the best premium pick available and the only reason he's not at Bont levels of selection is that Gawn and Grundy are so underpriced. Put it this way, if this was the Bolter comp where you have the 4 utilities, I'd be taking English, Marshall, Gawn, Grundy and Xerri in my starting side!