We also have a baby jogger citi mini. We had the single version for DD1 and loved it so much we've now brought the double version. Both weigh barely anything and I love that it folds and unfolds so easily. We've never used a capsule with the pram, we just used it as is.

Oh and Keta - DD1 had severe reflux. If you want any tips please ask. Luckily it looks like DD2 doesn't have it (so far).

EDIT - oh and good news today.DD2 put on 72g yesterday and the doc now wants her to try suck feeds at each feed (so try BF or bottle before doing a gavage feed).