I have used the TDS for 3 yrs on a 300 Hart killing deer to over 600 and coyotes out to almost 900. This year I put a kahles 3-9 TDS on a 300 WSM
and took deer at 467. Not exactly long, but mine is accurate to 700 based on my numbers in a program and actual testing. Before that I had used the B&C on the Hart. I do not care for the B &C, the TDS is really slick and works with a little work.
However, the key with the B&C and TDS is to find the exact distance in inches between stadias at a couple powers. You can call the company and they will give it to you. That way all you need is a ballistic program to run the numbers on MV (you will need that), altitude etc and a small 3x5 card will put you on. I have numbers for my 3-9 at 6x and 9x. That way you are not limited to one power as mentioned. Just have to be smarter than the simple instructions.
No they are not suited more much over 600 normally but they are relatively inexpensive (the Kahles 3-9 was $450 used and the Swarovski 6-18 was $800 used.) Their glass is second to none. A PDA will sell for under $100, a chrono for under $200 and exbal is under $50. Not much else is needed for their practical distances.
clicking is nice and essential IF it is long range and you have the time to look at the multiple drop charts, input data after multiple readings etc. I know I do that also. However, more shots are presented real world at 600 and under normally than over. The TDS is fast and reliable in that scenario.
Do not discount them because you do not have a $1000 scope and $2000 worth of computers and wind meters, etc.
Will give you a little hint, same system I mentioned above will work with the Burris B-Plex and the new Nikon Omegas and BDS reticles. All you need is the inches at a couple powers and a PDA.