One thing to consider is the lack of headroom in the a-line style popups. I don't remember which company(ies) make one that has an extra bumpout on one end, that gives you a vertical wall (with windows?) & horizontal roof above the kitchen area, and a diagonal wall/roof over the bed area. More room to stand up in.
Another thing we noticed when looking at them (we have not looked in earnest, though) is that they are heavier than we expected, closer in weight to a hybrid TT than a popup. (Caveat: we are only familiar with weights of older popups, 1980s and earlier - we went to full-height trailers in 2005. I know popups tend to be bigger & heavier now than they were when we bought ours.)