Adviser: I’ve not clicked any links or read any posts…
I got some GXP cranks a short while back and had a similar issue, no pennies at the time for a decent BB so I bought one of the £5 adapters.
They do work, sort of. Sometimes the crank spins inside the adapter (rather than the BB bearings spinning), and as such incurs friction making pedalling a bit more laboured.
I bit the bullet, bought a hope BB with the GXP adaptor. Much better and will almost certainly last me a lot longer.
I have a feeling, as the GXP and HT2 crank-tightening system puts different loads on their BB’s, that a GXP crank correctly tightened will kill an HT2 BB.