The main difficulty with the ledgerlok bolts going into 2x4s is that there is not a lot of width to the 2x4 you are going into. Ledger bolts don't usually fail by breaking, they fail because the wood around them fails. Not that it can't be done, but if I as an inspector saw you going with ledgerloks into 2x4s, I would tell you to have an engineer look at it before I would approve it.
The code calls out either 4 framing gun nails per stud, or 3 16d common nails per stud in Table R602.3(1), item 28. That may be cheaper than ledgerloks anyway, and that is probably the route I would take.