Is this for solo use or two person use? I think I would prefer the Duomid with Solomid XL inner for solo use as it’s has a smaller footprint, and has a side entry. You have the option to go sil to save some money if you want, or at least get a sil inner as the sil floor should be more durable than the DCF floor.
If this is for two person use with your fiancee joins you, you might prefer the Duomid XL over the Ultamid as it allows you to sleep on one side of the pole, and allows you to use an inner net without a pole in the center which is a downfall of the Ultamid 2 if you plan on using an inner. Without an inner, that’s not an issue.
I think the X Mid 2 is the best looking two person shelter on the market and is quite affordable. If you’re willing to accept the slight weight pentalty, I think it’s worth checking out.
If it’s your first DCF shelter, you can read up on whether or not DCF is the right material for you. I’ve owned 3 DCF shelters (Still own one) and think I prefer Silpoly. DCF is very bulky to pack and the complete lack of stretch is both a blessing and a curse as it’s not very forgiving to a bad pitch.
If you are dead set on the Ultamid 2 or Duplex, I’ll say it depends. The Ultamid is pretty bomb-proof, is extremely well made, and is aesthetically pleasing. the Duplex is lighter but if my previous Z-Packs gear is any indication, it looks like it was sewn in someones garage – not that it’s not functional, but I’d have a hard time paying $600 for gear that looks like that. It’s also not as stormworthy, though with a Hilleberg available, you may not need another storm worthy tent. I’ve only been in a Duplex once and floor space was tight for two, but had nice volume (shoulder room).
So out of those two for me, if I was planning on using it in mild conditions and wanted bug protection I’d lean Duplex, if I wanted something more stormworthy and I planned on using without an inner net or with bivies, I’d go Ultamid.