So this requires making dust payments to a constantly reused address
in order to (ab)use the blockchain as a messaging layer.
Indeed, this is more SPV compatible; but it seems likely to me that
_in practice_ it would almost completely undermine the privacy the
idea hoped to provide; because you'd have an observable linkage to a
highly reused address.
It would also more than double the data sent for the application where
'stealth addresses' are most important: one-time anonymous donations
(in other contexts; you have two way communication between the
participants, and so you can just given them a one off address without
singling in the public network.)
This kind of binding was intentionally designed out of the stealth
address proposal; I think this scheme can be made to work without any
increase in size by reusing the payment code as the ephemeral public
key (or actually being substantially smaller e.g. use the shared
secret as the chain code, but I should give it more thought)
This is fundamentally more expensive to compute; please don't specify
"uncompressed".
This appears incompatible with multisignature; which is unfortunate.
I'm disappointed that there isn't any thought given to solving the
scanning privacy without forcing non-private pure-overhead messaging
transactions on heavily reused addresses. Are you aware of the IBE
approach that allows someone to request a third party scan for them
with block by block control over their delegation of scanning?