target enrichment for resequencing using Ion Torrent

[JWJH]

Hi, first time posting here and I'm not sure if this goes in here. Please let me know if this should be somewhere else or if this question has already been asked before (I've tried looking through the rest of the site but couldn't find anything).

I'm planning on using the Ion Torrent PGM with 316 chip for a targeted resequencing experiment with a very large target region. I'm currently trying to figure out the best way to enrich the targeted region and am sitting on the fence with Ion TargetSeq and SureSelect but for the meantime, would like to try a quick run of the lab's new Ion Torrent PGM to try to find out how to work the thing (no one in the lab has any NGS experience).

I'm looking to enrich a region that's nearly 145kb using Long-range PCR for the time being but am unsure if this is a good idea and have a load of other questions as well...

For example, I'm looking into selecting a good LR-PCR polymerase and have a few candidates in mind (KOD FX NEO, Expand 20kb PLus PCR System from Roche...etc) but I've realized that they all need different amounts of genomic DNA template. KOD FX NEO states that they recommend 50ng of genomic DNA template while Expand 20kb PLUS states a recommened final concentration of 250ng - 500ng)..does anyone know why the difference is so huge?

Thanks and apologies for the long post