I've just picked up a new Mikrotek i800 to scan my 4x5s (mostly chromes, a few negatives), and I can't seem to get the scan to even vaguely resemble what the chromes look like.
I'm very adept at Photoshop, so that's not the problem, and I can easily deal with color casts.
The problem is one of tone and dynamic range. Even scanning in 48-bit HDR with Silverfast or in 48-bit RGB mode in Scanwizard the scans are extremely flat and I can't seem to lift detail out of it. The slightest curve / level adjustments will blow out brighter midtones. Shadows are completely blocked and unsalvageable. For a scanner with a very high dynamic range (D of 4) I expect more than I'm getting.