I've been a fan of spruce tops since I played my first Artinger guitar three years ago. I wound up buying an Artinger semi-hollow with a European spruce top, and that has been my main blues and jazz axe for the past three years.
One day in Matt Artinger's shop, I was able to A/B my guitar with the maple-topped version of the same guitar that was reviewed in Guitar Player magazine. The maple top was way too bright and shrill for my tastes.
Since I bought the Artinger, I've picked up both a PRS spruce-topped HB and a Hamer Newport with a Bigsby. To my my ears, ALL of these guitars sound SIGNIFICANTLY sweeter and more mellow than similar guitars with maple tops.
Actaully, my wife got me a maple-topped PRS for Christmas; we went back to the store and A/B'd the maple top against the spruce top, and even SHE agreed that there was no comparison, and she's not a guitarist.
Stephen - compared to the 335's and Ibanez semi-hollows that I have used in the past, the spruce top is a lot more acoustically resonant and harmonically rich than maple-topped or ply-topped guitars. I find that I hear more of note's initial transient attack out of a spruce top, which means that I can play softer and with more feeling without getting lost in the mix.
Along with the snappy attack, I think that the spruce gives the guitar a warmer midrange, which sounds really nice for mildly overdriven tones. I go for a sound that is full and rich, but not necessarily "distorted", and the spruce top excels in that area.
That said, you also have to consider the guitar's other build characteristics outside of its top. The sound quality of my Artinger is head and shoulders above both my PRS and Hamer.
Of all the guitars and amps that I own, the Artinger plugged into a Fuchs ODS 50 pretty much covers any jazz or blues tone I ever need.
PRS has a hollow bodied spruce top that is very nice sounding. Played a friend's last weekend and was very impressed with the clean and dirty tones. Midrange was very sweet and overall the guitar had tone you could fall into. Notes floated like the air current moved them up and down when played clean and with some overdrive it was smooth and midrangey. Don't know what pickups were in it. Believe they were PRS of some kind. Impressive sound for around $2K.
Stephen - actually, I CAN compare the two, and given that both guitars are strung with DR Tite-Fit .011's, the comparison might be somewhat meaningful.
Acoustically, the Newport is definitely brighter and has less low-end response than the PRS. Part of this may be attributable to the fact that my Hamer has a Bigsby and a Tune-o-matic as opposed to the PRS, which has a McCarty-style stop bridge/tailpiece combo.
Amplified, the two could not be further apart. The Phat Cats are phenomenal rock pickups; I get a great rockabilly tone out of the Hamer, and by backing off the volume a bit, I can get some very nice smooth jazz tones 'ala Jeff Golub and Chuck Loeb.
The PRS's humbuckers complement the acoustic sound nicely, and when played through a fat tube amp (like a Mesa Blue Angel) will give you a nice warm jazz tone. The PRS sounds WONDERFUL with moderate overdrive - you can get some amazing tone textures with the PRS HB into a Fulldrive and into a tube amp.
By comparison, the Hamer has more growl, snap and bite when you overdrive it.
The PRS would be my choice if you were looking to cop a more traditional "jazz archtop" tone with the added flexibilty of adding mild amounts of overdrive to the sound. The Hamer, to my ears, lives more in the smooth jazz/rock/rockabilly world.
One other thing to note is that the necks on these guitars are markedly different. They are both chunky, but in different ways. The Hamer neck just seems BIG, kinda like a Les Paul standard, while the PRS feels thicker front-to-back - more of a U-shaped neck. I would advise you to try to get your hands on both before you buy, but if you're the type of player who goes for a "wide/thin" type of neck carve, neither of these guitars will feel instantly comfortable to you.
All that said, if I had to choose one guitar to cover all my jazz/blues/rock bases, I would take the Artinger semi-hollow hands-down. It simply is the most tonally flexible intrument that I have ever played.
Well I've finally surrendered to the spruce/mahogany mojo and got a Baker RF! Wow, what a smooth, FAT, articulate tone! The look and feel, the craftsmanship, the resonance and tone- this is a seriously killer guitar.