DT vs bar ends
I've used both downtube and bar end shifters, so I'll try to describe the comparison. If you're running both as friction shifters, the mechanics and function are pretty much the same - both provide a direct linkage to the FD. But bar ends need longer cables with more bends so your shifts will be a bit slower. Bar ends use your last 2 fingers to operate and put your arm in an awkward position IMO. DTs use your thumb-index finger on the lever though the shift is actually done with arm and wrist motion, which is strong and won't fatigue easily. DTs require that your hand has to leave the bars to shift, so on occassion you'll have to delay a shift due to bumpy roads. That's generally not an issue (unless you are racing). If you were happy with bar ends, you could probably be happy with DTs as well. You'd save a little weight with DTs over bar ends and have fewer cable failures. Either should work well for you, so maybe your comfort is the best guide.
Oil is good, grease is better.
2007 Peter Mooney w/S&S couplers/Terry Butterfly
1993 Bridgestone MB-3/Avocet O2 Air 40W
1980 Columbus Frame with 1970 Campy parts
1954 Raleigh 3-speed/Brooks B72