I havne't tried a Beco personally to know, though that's really super dumb if that's the only way. I've never wanted to try an internal harness carrier ever. Though I don't think you *have* to use the internal harness if you don't want.
The Ergo does have buckles for the straps. They're where like 95% of SSCs have them - bottom sides where the webbing meets the body. In a front carry you can always unbuckle the straps and cross the straps across your back (like a mei tai) and buckle each shoulder strap on the opposite body side. Some SSCs do this A LOT better than others (depends on padding and how curved the padded straps are). I've never tried with the Ergo because it's only used in a back carry 95% of the time. The Angel Pack (APLX) does this very well and I liked it for front carries. You can also unbuckle the Ergo straps in order to get the carry right for a hip carry (something else I've never tried b/c I have a ring sling for that ).
See, this board only gets more awesome. I never knew you could use an SSC in anything other than a backpack-style carry (on the front or back, obviously). I actually think I recall that you can't use a Beco (or aren't supposed to) in a back carry...but I never got that far with it anyway. The buckles are up on the top front of your shoulders, and you have to open the front to get the baby in and out, since you can't just take the carrier off--the baby would go with it! It's a horrible design. I honestly don't understand why it would even have been invented, unless I am deeply misunderstanding it (but I don't think so).
You totally can use a Beco with a back carry! I think all of the Becos are okay for back carries (at least according to them). That's why some people love the internal harness so much, it helps them with back carries.
OH, I just realized...I'm thinking of the fact that you can't forward-face in them, not back carry. Whoops, my mistake! (It's been a long time! But that was a real issue for us at the beginning, since DD refused to be carried parent-facing. True for most good SSCs, though.)
Last edited by cactuswren; 02-11-2012 at 04:49 PM.