What format were those original Kodachromes? Assuming the quality must be better than the scans posted, the quality is stunning!
Realistically without pixel peeping it's hard to really compare as with suitable sharpening you can make most general scans look excellent at these sorts of sizes. Frankly, armed with a decent negative/slide you can get excellent results out of really quite humble scanners, assuming you put the time in correcting colours etc. Decent scanners come into their own when presented with dubious negatives, saving otherwise unusable images. At some level though, if the negative is bad enough, there's nothing much that can be done to pull the contrast out, and all you see is dodgy film grain/scratches etc.