I got the teflon lined one and sprayed a shot of dry graphite down each end for extra measure. I may try a high-end bicycle cable for the choke—as it's getting balky as well. 

Note: If you're not certain that your throttle cable is fully opening the carb(s) at WOT, have an assistant floor the gas pedal while you look at the linkage under the hood (engine off, of course). If the carb(s) are not fully open when the anchor point of the throttle cable is directly in line with the cable support bracket, well, this a problem. Just a couple of degrees shy of alignment makes a huge difference. As I mentioned, I discovered that my carbs were only 4/5ths open at WOT. 

I repositioned my cable anchor point a few degrees before TDC so as to allow for any stretch in my new cable. 

Before BMW and fly by wire Rolls-Royce used a mechanical linkage for the throttle it was a superb bit of engineering, in fact the exact same ball joints in the system were used from 1904 until the fly by wire system came into use.

Bicycle cable housing works great. I used Jagwire brand to do my throttle, choke, and heater control. I've had less problems with it than the original stuff.

Yes, mechanical can be tricky. On my Corvair there are various pivots under the car, then in the engine compartment, finishing with this cross piece to activate both carbs at the same time. A little bit of wear in any pivot, especially in the crossover, and your engine stops responding as you want. On the cross bar, the carbs become unbalanced. I made teflon bushings for mine to take up the slack.
 

Actually a cable is probably the best. Fly-by-wire (electronic) actuation would be complex and difficult to set up for a carb (not to mention duals!) Hydraulic would be heavy and difficult to adjust. Mechanical (rods and levers) is as hard to adjust as a cable, is more complex and heavier, and has much more free-play. Have a look at a 1960's or earlier North American car, especially an automatic, with the transmission kick-down mechanism.

The only weak spot in the Mini cable is how the core connects to the throttle lever and the issue of the core strands fraying. If you position it properly, including the use of the firewall stand-off bracket (see picture) it will stay away from the hot surfaces.

I swear by modern cycling cables, teflon lined, corrosion resistant, super strong. The technology behind cycling components is really quite incredible.

Just replaced my dual SU's after adding new float needle valves.  There has to be a better system for a throttle actuation than that crummy cable!  What is that one you mentioned with teflon?

I learned the hard way that it is easy for that cable to get too close to the exhaust, melting the plastic, causing it to stick.

Did you go for a standard cable or the teflon lined one ?

The difference between the two is marked.

I replaced my throttle cable last evening—it was feeling a little ragged and I though it could use freshening.  Wow! I had no idea how rough it had gotten. After replacement it feels like I have a different clutch & flywheel and a smoother and peppier motor. No more jerky take-offs, the motor returns immediately to an idle when I take my foot off the pedal, and bipping the throttle at a downshift is flawless. What a HUGE difference!

Bonus: It turns out that because of the angle of the old throttle cable and throttle arm, I was only at 4/5ths throttle at WOT.  After correctly aligning the throttle cable with the sweep of the arm, I am no longer leaving anything on the table, throttle-wise. Who knew?