As far as I can tell, infection invariably leads to the host consciousness being subsumed and destroyed. Memories do not equal consciousness.
To illustrate this, imagine you were flash-cloned. You and your clone share the exact same experiences, memories, and morals. Now, let's say you die immediately after the cloning process finishes. Your consciousness doesn't somehow "transfer" to your clone because you share the same experiences, you die, and your consciousness dies with you. Your clone is a discrete entity, and will maintain its independence from you.
When Captain Keyes was assimilated into the Flood, he retained a brief measure of individuality. However, when his memories were absorbed by the Flood, Captain Keyes, for all intents and purposes, ceased to exist. His consciousness did not "transfer" to the Flood, it no longer existed.
If an AI removes data from another AI, deleting the original as it goes, and then, after stripping the other AI of all its accumulated data, it destroys the AI, the destroyed AI doesn't remain active in the data removed from it. The original AI is gone, its data now belonging to the other AI.
If you were to be integrated into the Flood, once your memories are stripped away, you cease to be. Those memories are now the memories of the Gravemind, and your body is but a shell, a puppet dancing to the Gravemind's strings. The Gravemind can accurately replicate your consciousness, but that consciousness is not you. You are dead and gone.
Suffice it to say, there is no benefit, no advantage, to joining the Flood. You will die, and your former body is now nothing but an empty, hollow shell.
If you use PFC Jenkins as a counterpoint, you must remember that Jenkins was an outlier. He was infected by a particularly weak infection form, and so was able to maintain his individuality. This was possible not only because of the age of the infection form, but also the lack of a Gravemind. Had Jenkins been attacked by a full-strength infection form, or had a fully-formed Gravemind been present, it is virtually certain that Jenkins would've met with the same fate as Keyes.