In comparison, all of those tools are useful. I have worked with PC3000 DOS, PCI and then UDMA. Just for experience, I tried Atola, SD, DDI, etc. They are all good tools. To better display the difference between those tools, there needs to be a diagram. Something like.
DDI can do: B, C
Atola can do: A, B, C, D
SD can do: A, B, C, F, G
When PC3K UDMA + DE can do: A-Z
Overall, yes, all those tools are useful for cases they can be used for. If you have one tool and don't have other, means you are less likely to fix a drive with which this particular tool is not really good with. I hope you know what I mean.
Many people praise DDI, which I still use. But I only use it when I do not have a slot on PC3000. DDI is imaging tool only, which can do 90% of Ace's DE. The disadvantage of it is not being able to easily browse through sectors, load, and save sectors, work via Utility (for example trick WD Marvell's calibration and then use DE to image by heads), and some other things. Nowadays you can work with DDI via Windows, but still some of the features DE Imaging Utility (make data copy) offers are not covered. Build map for the win

As far as SD, it has the same, if not better, support for flash devices, USB drives etc., but when it comes to working with firmware of modern drives (WD USB, WD Marvell, Seagate ES2 and .11), it is behind by FAR, even some basic features are not included.
Now, pricewise, would it make sense for a guy who like to ride bicycle once a month to buy a $6,000.00 mercedes bike, which weights only 1.9lb? Not really. If that guy becomes a professional biker, then yes. Same thing here, what is a point of having an almost $15,000.00 tool, when you cannot understand basic mechanics and firmware structures of hard disk drives? Having PC3K won't make you a better data recovery tech, it gives you an ability and apprtunity, if, and only if, you have a GOOD idea of what you are doing.
@pclab - take your time, start from learning basic mechanics and electronic parts of hard disk drives. Learn file systems. Then read SD manuals, they have a starting idea about firmware of drives, etc. Having problems? Ask here or ask SD lab. If something you have NO idea how to work with, send it to another company. Later on, you will start understanding the whole concept of data recovery industry and won't need to re-send any of your data recovery projects. There is publicly available material online, it is just VERY hard to find. So if you do a good job at searching for it, you will find more than you need. Here is a doc I found within 2 minutes of online searching on
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