Quote from Martinghoul:
Sorry, nel-san, I think there's actually a misunderstanding... I wasn't explaining what I meant clearly enough.
When I say repos, I am describing their use when you own the underlying bond and lend it out in the repo mkt. In such circumstances, repos have relatively negligible interest rate risk (relative to the duration of the position itself). You might have been thinking of repo as used by money funds, i.e. a short-term money mkt instrument, where you simply lend cash in exchange for govt collateral. The latter is not what I am describing, but I have a feeling it's what you're referring to.
To summarize my point:
Duration management using govt bonds with repos as an alternative to swaps is identical in terms of balance sheet consumption (i.e. cash outlay). In such a context, the only fundamental difference between swaps and bonds is credit: LIBOR basket vs govt.