Okay Chris. As I read it there are two issues here.
1/ Your faith, or rather lack of it, in electrical systems.
2/ Your desire to use a two cell li-po as a power source.
To my mind the easiest solution for you is to use a standard 4, (or 5) cell Ni-MH battery
The 4 cell will produce a nominal voltage of 4.8v, and the 5cell a voltage of 6v. Both are within the range of most small servos. (Certainly 4.8v will work all small servos)
I don’t know the weight of a (say) 800mAh 4cell Ni-MH pack (Pack of 4 AAA size cells) but they are not much more than a Li-po of the same capacity. In fact you would probably still need to add some extra weight in the nose of the Quark to balance it. So instead of adding lead, why not take the easiest answer to you voltage problem and fit a bigger (heavier) Ni-MH battery?
As for voltage regulators. Linear regulators can sometimes have thermal issues. (They can get hot and fail when handling high current loads, like when using lots of servos for a lot of the time during the flight.) This can be overcome by allowing good air cooling to pass over their heat sink.
Switching regulators, (as most UBEC’s are) run much cooler and although they used to cause RF interference problems with the old 35Mhz rx’s, if you’re running 2.4Ghz they will give no problems.
If I may say so Chris, your concern about electrical failure by virtue of the number of items in circuits is not born out in reality.
I too have read and heard of cracking wires, so called ‘black wire’ corrosion, dry joints, ect yet I’ve been flying model aircraft for 7 years now (gliders and electrical powered planes) and never had any such problems. Modern day electronic devises are very reliable.
For instance, the miles of wire and circuits in your car are very complicated, with hundreds of joins, exposed to all weather conditions yet still it starts ‘on the button’ doesn’t it. (The lights work, so do the windscreen wipers & washers, indicators, heater fan, engine cooling fan, stereo system, brake lights, horn, heated window, ect ect.....)
If you’ve already bought the Li-Po then I’d get a 4.8 or 6v UBEC. If you haven’t got the Li-po yet, I’d go for the 4 or 5 cell Ni-MH. You wont be disappointed. :wink:
Keith