Can you put racks on the soloist for your hauling needs? I'd say sell it/trade it in, but I'm not sure the soloist is what you're looking for. Now if you could trade it in for a cross check (never used one but that's just based on the forum reviews) or another cx or touring bike you like, then rock on. On the other hand, if you can run errands and stuff with the soloist (and fit fenders), I'd go with that. Just to me errand/rainy day bike means racks and fenders (not necessarily not aggressive position, though.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"