1) Ilaflon is not SIG's answer to Tenifer. Nitron is, and it works quite well.
2) Ilaflon is a silicone based powder coating made by ILAG in Switzerland. When the new SIG owners took over, they decided to scrap the plans to bring Ilaflon to the US (probably because of production shifts), and decided to go with Nitron finished stainless for US production. P220/P245 production in Europe is Ilaflon finished. P220's made in the US are blued.
3) Is Ilaflon worth $100 more than blued? I don't think anyone knows (except maybe one of our European friends). Blued SIGs are known to rust when not cared for properly. Ilaflon is probably better in that respect, but we don't know if it wears better (although it reportedly does).
Good luck.