what this brings to my mind is Steffon Armitage (1m73). He's the best fetcher in the world atm, has been for a little while now, not surprisingly he won ERC European player of the year, which isn't nothing. I don't play Rugby, but what I can tell you from observation is a backrower who's short, the pros are his center of gravity is low, and chances are he'll be quicker than a 1m95 120kg giant in all facets of his game.
Cons from what I've seen being short is awful for ball-carrying (being too tall too, with rare exceptions, 2nd rowers are tackled easily). Armitage himself has his moments with that but is more often than not stopped at the root, while generally other short forwards like Thomas Domingo, or others who aren't short per se but "look short" and play a "short man" type of game like Szarzewski (1m80) or David Pocock (hard to realize he's actually 1m84, well, listed as...) or props who are extremely compact and stocky you'd think can carry well with their physical density really don't (Nicolas Mas, or even Healy who reputed for his strength, I'm always surprised he isn't a dominant carrier). So props can't carry for shiit, hookers can't either.
The best ball carriers around are the Louis Picamoles, Antoine Burban, Gilian Galan, Damien Chouly, Ben Morgan, Billy Vunipola, Sean O'Brien, Jerome Kaino, David Denton, Duane Vermeulen...all third rowers who happen to be at least 1m90 tall and all around 110kg or more. That's the classic carrier type.
That's the main distinction I'd make. Short, you can develop into a nice fetcher, quicker off your feet. Tall= ball carrier, platform to operate with (offloads, go forward).
Both can tackle well but it's true those shorter props for e.g. with their short arms will miss tackles other bigger guys just won't because they cover more ground, are longer, bigger.
P.S.: it SHOULD be said also that that enumeration of big, tall loosies I made up there happens to be a list of today's most popular third rowers, not just good ball carriers. All those guys are starters on Tier 1 nations (one or two exceptions). That should say something about today's situation on backrowers and what works. Steffon Armitage is an absolute, absolute anomaly.