Hi Hendoendo,
I still have not compared the the TDI to the SD 2200 even though I have one of each. The main reason is I have to find a spot where it is basically noise free for the SD to shine. Any testing in town is of little value because the TDI blows the SD away simply because the TDI is not as affected by typical civilization noise as the SD's are.
As for depth, the TDI does quite well. I suspect under ideal conditions, the two detectors will be reasonably close on the small gold, say in the 1 gram or less, but the SD should have a clear edge on the larger stuff, maybe 1/4 oz to 1/2 oz or larger. Part of this has to do with the actual setting of the detector also.
The TDI is not designed to compete with the SD but to stand on its own merits. The waterproof coils, the ability to hunt in fairly noisy environments are real advantages for the TDI. The additional ability to use the detector for other types of hunting also helps.
As for sheer depth and sensitivity, the ML's appear to push the limit, thus they are much more susceptible to external noise. The TDI is not pushing the limits so it will not have the ultimate depth capability, but will not suffer as much in noisy environments either. So, there is always a trade off in this respect.
People using the TDI are now starting to post more about the sizes of gold found with some indicating down to 1/1/2 grains. Finding larger gold obviously would be easier, but most gold found here in the US is small, so doing well in the small category is a real plus.
The TDI is more versatile in my opinion, but because of the controls, it is also easier to set for different capabilities and not get the maximum depth capabilities on certain size gold or other objects. Again, much of this is a trade off. A good example is best explained when discussing hunting for silver coins where the ground balance control can affect the depth as well as the trash that might be detected also. Adjust the ground balance to reduce the possibility of detecting nails and other iron junk and you reduce the depth on silver. Knowing how to run a quick test on targets helps eliminate this condition, but it does take knowing more about the detector. In other words, one can run with a different GB setting and then make a quick test on suspected targets and thus reduce the depth loss, but at the expense of ease of use.
The same would hold true for certain sizes of gold. Here the condition is quite variable because it depends upon the gold itself. In some areas gold in the 1/4 oz range will generate a low tone, while in other areas, even multi-oz gold creates a high tone, so knowing more about the gold helps in the settings of the TDI. Set it up correctly and all goes well. Set it incorrectly and one can miss gold and not know why. So, in some aspects a person has to know more about the detector because of its features and controls. As a good example, lets say a person knows the gold always gives a high tone, then selecting high tone only reduces the noise level and does eliminate other bothersome targets. If however, a person selects high tone and gold quickly changes tones, then one can miss the bigger stuff also. So, this is why I recommend knowing both the detector and the characteristics of the gold where one is hunting whenever possible. When in doubt, use the both tones.
The point I am trying to make is if a person doesn't take time to learn the TDI and how each control affects the operations, one will not get the maximum performance from the detector, thus making it easier for a detector with limited adjustments to appear better.
So, I guess it comes down to opinions as much as anything as to which is better.
I am not trying to avoid your question but to try to explain the difficulties in answering it.
I hope this helps.
Reg
