We have one of the original Seed Shuttle tenders which was one of the first built to hold boxes and the past two years we've borrowed a bulk tender to help with beans.  90% of the time I like the boxes better, we buy some bulk beans and just refill the boxes we have on the tender when we do that and zip tie the lids back on.  We don't have a scale on our tender but I wish we did because the downside to the boxes is it's hard to tell how much seed is left in one as your filling the planter.