I sincerely doubt Suzumebachi's instant kill would be any more effective than anyone else's instant kill (that is to say, not.)
As for blowing of his head; that'd be even less effective. His hollow form showed absolutely no noticable drop in power despite having a gigantic hole punched right through the middle of it, Ichigo's hollow form has shown itself to be effectively indestructable, and any injuries you do manage to inflict on it are promptly ignored and regenerated moments later. I don't imagine blowing off his head would have any more effect than anything else.
It's worth taking a look at the fight between the Vizard when he was suppressing his hollow too; look at how it's fighting there. The thing would be a nightmare to face on the field, it's actively using it's regenerative abilities to reshape it's body and launch all kinds of wierd fucked-up attacks (giant mouth snake thing wat). I think going up against Ichigo's hollow form in full cry would be a very stupid move unless your Aizen, and thus have the one single weapon capable of actually stopping him with your OP impossible-to-break illusion bullshit.
Of course all of this is just theory, but the fact that Ichigo's regeneration gets called out as being special Instant regeneration (and it is called out with a different kanji in the manga, it's not just a translation thing) is pretty goddamn scary, since we've already seen that normal fast regeneration on a Captain level monster is serious buisness, and that regeneration couldn't regenerate internal organs, something which Ichigo's hollow regeneration seems to have absolutely no problem doing.
The only reason Ichigo hasn't eaten everyone else on the cast yet is because he keeps somehow winning his mental battles with his inner hollow. That and he's Kenpachi-lite, which i must admit does help.
I feel i should also add that Ichigo's hollow has never actually been seen fighting at 'full power' so to speak, and that Ichigo himself seems horrifically incompetant at taking full advantage of some of his abilities. Something which his hollow self seems more than capable of doing.