I’ve owned the Anfibio Sigma TXL for a couple of months now and have done several day trips two-up, solo and sailing. They’ve all helped give me ideas on how to refine the boat to my needs.
On purchase I got the optional Multimat airfloor, additional foam block seat, paddle leash and use my old Anfibio DeckPack on every trip. I also got a spare skeg patch and mounted a second skeg under the bow – it made things worse.
Here’s a quick reappraisal of the Sigma TXL followed by a list of modifications which have worked for me. Got packraft tips of your own? Let’s hear them.

Spacious solo
Light for its size
Room for 1.9
TubeBags very handy, even for day trips
Level solo trim (unlike Rebel 2K and similar)
Multimat floor’s benefits are just noticeable (good to sleep on, too)
Broad, thick front seatbase spreads the load: less floor sag when solo
Thicker 420-D floor extension ‘bumpers’ over bow and stern
Variety of set-ups and sitting positions, solo or two-up.

Stock skeg mounted too high (or too small)*
Inflatable front backrest lacks support
Optional foam seat block too hard
For me, the paddle leash was inferior to a regular mooring line
A dump valve in the seatbase would be nice (instant deflation)*
Reduced floor space when two-up with Multimat (depends on your sizes)

*Skeg repositioning on TXL and lock-open seat valves for all are scheduled on future Anfibios.