The big draw of ECO  hubs (at least for me) is  that  it's something  that can be  done in the driveway in about  the same time it would  take  just to  service the hubs.  And  it's just  as  easy to revert  back to stock.  Also factor in the price at  around $2500 shipped
Where 3:07's will  require  pulling the axels, dropping the drive shafts, cracking  open the pumpkins, etc, etc.  Having someone do the work  is pricy  (especially  if they really  know  these  trucks) and the work is mostly all  geographically isolated. The cost of  the 307's is historically  anywhere  from $3000-$5000  for just a pair of  pumpkins (yeah, the originally  cost about $80  ea  at auction but "supply and demand"...or blatant wallet rape depending on your perspective).  The price may be  falling as  people  shy  away from  them in favor  of  the,  IMO  better solution of  ECO hubs.  I'd not saying that 3:07's are still  not a good deal  at  $80  each, I'd just  rather  the flippers who  have controlled the pricing up until  now  keep  them.  The 3:07's  are FAR  more complicated to  revert back  to OEM should  someone wish to do so for whatever reason.  And shipping a couple pumpkins  across the  country  is not  cheap.
Personally, I'd always MUCH rather support  someone who  is actually making a product.. opposed to just flipping old surplus (especially  when it's for big profit justified by "supply and demand").
ECO  hubs are a win/win in  my book.    There's no  question as to which is the better/smarter purchase/install,  IMO.
ymmv