I reckon you'll do much better with a dedicated film/slide scanner, or a more 'highend' flatbed scanner with film/slide support.
The 3490 is exactly the one I've been thinking of getting myself, but I'm not interested in the quality of scanned slides.
Some good reviews for the 3490 click here, click here & click here.
The Canon 4200F has similar specs & price. Independent reviews click here & click here (this one is not good), & user reviews click here & scroll down.
I'm more inclined towards the Epson, mainly because it has a shorter depth - 41.9cm as against the Canon's 47.3cm. G