In terms of absolute resolution as measured by charts and pixel-peeping, 35mm velvia slides scanned with a high-end scanner are competitive with a 20MP full frame dSLR, except way more grainy and mushy (you need to sharpen tons, adding additional grain). So you'll then get large format enthusiasts saying "large format is 300 megapixels!" but what they forget is this:
In terms of how prints "look" three megapixels beats any 35mm color film print as this very site proves:http://www.luminous-landscape.com/reviews/cameras/d30/d30_vs_film.shtml
Medium format may resolve a tiny bit more detail if drum scanned, and large format may resolve a little more than that (though due to issues of film flatness and bad lenses/diffraction, large format is barely better than medium format, just less grainy, which isn't an issue with digital). Medium format film is still grainier than even digital point and shoots are. And most of the detail is fuzz. Digital cameras resolve >100% mtf until they hit extinction, at around 80lp/mm on high-end dSLRs. Velvia, the subjectively sharpest color film, falls to under 100% mtf around 20lp/mm, hence grain/fuzz issues.
For all REASONABLE purposes, unless your viewer is going to study your prints under a microscope, the Canon 5DII should equal or surpass large format film, though APS-C digital may not. High-volume photographers have all gone digital. David Meunch, the big name in color 4x5 landscapes, switched from a Linhof 4x5 to a point and shoot, which he uses handheld if needed.
If you want to print HUGE (wall-sized) and do near/far compositions, a tilt/shift lens and tripod may be worth it. Otherwise a couple IS zooms and some filters may suffice. But digital is flexible so you can bring the tripod only when you need it for stitching/focus stitching (to defeat diffraction)/hdr/etc.
That said, there is something "nice" about technically perfect huge (40''x50'' or larger) large format prints that I've yet to see even from medium format digital--and some films have nice, inaccurate but dramatic color rendition (which only matters if you don't post-process, but it still looks cool). But if you plan to shoot more than five images a year and spend less than a thousand dollars on each print, a full frame dSLR will look as good as large format film on first impression, better than medium format, and will be much better than either in general by virtue of being way more flexible and less expensive past the initial investment. There might just be a tiny bit less detail than large format if you walk up to the print and squint, but does that matter to your average viewer?
Personally, I don't like stitching since the best light is fleeting, but digital gives you the option to stitch if you want to make huge prints so why not? Three stitched dSLR images will trounce large format in terms of subjective sharpness and likely surpass it in terms of actual detail, too.
And, full disclosure, I shoot large format so I've had to convince myself there's a difference in image quality. Ask people who've switched to digital, they may disagree and say dSLRs already beat large format. Almost no pros still shoot large format.