I decided to make the transition from upright to recumbent primarily for comfort & experimenting with fuel efficiency, I'm beginning my second season with it now and yet I'm still undecided if I'll pursue aeromods, be it just a fairing or a full velo shell...
...it is a "natural progression" as you say, the advantages both undeniable & profound but there are additional considerations that continue to give me pause, some of which I've mentioned previously (expense, maneuverability, ergonomics) and as the 'T3' experiment
has already succeeded in it's original goals, last season spent in testing - I'll prolly not do much other'n just play with it this season, aside from whatever refinements may crop up.
This is one of the primary reasons I've been hesitant to velo, admittedly it's got very little to do with practical application or fabrication & just the limitations of my shop space, I came very close to building a "ship in a bottle" lol, another inch in any dimension and it'd not fit out the door - so any aeromods would have the additional complexity of having to be quickly & easily removable, even with a full velo shell I'd not want to be forced to store it outside;
Still, the temptation is there - not just for the almost irresistible preformance advantages & all-weather comfort, but for the opportunity to tinker as well. While I've not committed to building a velo shell, I've not stopped hunting around for different build techniques, materials, shapes & styles & so far while not the most aero, I've been tempted by something like this example below as it's simple, all flats construction would ease both budget & build;
...and would at long last provide a place to mount a blasted cup holder, which may have a disproportionately predominant priority on my "to do" list lol