Well, I was making the (slight, IMHO) stretch that since Sniper replaces skirmish that I could apply Swift Hunter to the Sniper Progression.
And YES, I'm jumping through a lot of hoops to max the damage on a single shot, but a lot of them I would still do for a normal, Rapidshot swift hunter who uses some trick to move with a Full-attack. Wich just means that you're sacrificing at least 150-200 points of damage for the single-shot mechanism.
So... I guess it depends on your group. If your group is generally VERY unoptimised, then you might just play it like that. But if not, then you're probably going to feel underwhelming.
Now, my suggestion for a sniper is something entirely different: Arcane gish with a two-level dip into arcane archer. Instead of dealing massive physical damage, you basically shoot bombs into the melee.
Build suggestion:
(Any) Elf Warblade1 or Fighter1/Martial Focused Conjurer 6/Spellsword1/Abcha5/AA2/EK rest.
You basically use Imbue Arrow to lob damage (or other) spells at people at stupid ranges, and you're still basically a Wizard, which means you have backup options.
You can also do it as a sorceror, with the possible benefit of the weird sorc spells.
The other option is Spellwarp Sniper, but it's rather close range.
And the final option is a fairly tricked out Warlock. As a suggestion which I have not checked vs. legality:
WarlockX/Mystic RangerY/HellFire Warlock3/Eldritch Disciple10
The idea is basically to use the Ranger spells that grant sneak-attack with the EB.
I also tried to homebrew a sniper once, it sort of not got discussed further, well, it's here:
http://brilliantgameologists.com/boards/index.php?topic=4606.msg153566#msg153566 ; There are some things I don't like about it in retrospect. Like the once-every-other-round restriction.