I looked at the Posi-* line of products online - haven't used them or seen them in person. It may be that my rant following against the Scotch-block style connector doesn't apply - I'll reserve commenting on the Posi stuff until I get a good look at how it connects to the supply wire. Meanwhile - here's my rant against those connectors that tap into a wire by damaging it with a blade. (Since I already wrote it before I looked at the Posi design)
Tap connectors that use a blade to cut through insulation and contact the conductor are perfect propagators of galvanic corrosion. Besides putting dissimilar metals together and passing electricity through them - where one becomes an anode and the other a cathode resulting in the DEFINITION of galvanic corrosion - they also break the moisture / oxygen seal at that very spot to accelerate the corrosion. While they nick the conductor reducing it's amp capacity and if the wire is carrying close to capacity already - and now with your tap you are going to increase it - you can add impedance-induced heat to the mix, and deliver less than optimum voltage to every load on that circuit.
BAD idea. Nearly every connection failure of other's bikes I've had to fix, has been caused by the use of this type of connector, and there have been MANY. Don't use them unless your wiring is not intended to be permanent. Say you have an enemy, do all the circuits with these parasitic connectors, and sell him the bike. The guy who invented these should be strung up by his balls. I caught a U-Haul guy using them on my truck to connect the trailer I rented - he was aghast at my chewing him out for damaging my wires - but he didn't know any better, and for sure was doing what his boss told him to. Bless his heart.
If you don't think this is good advice - google "galvanic corrosion" with "wiring" and read what you find.
But then it also depends on your work standards. Are you comfortable with saving a couple minutes here and there weighed against what you know isn't a good connection. When it's done, and you have installed wire taps all over your bike, how comfortable are you riding at night on the Al-Can highway 200 miles from nowhere? Install enough unreliable connectors and your MTF (Mean Time to Failure) approaches zero. This problem was demonstrated very well with the first big computer, the ENIAC. Before solid state circuits, it was all vacuum tubes and hand wiring - extremely complex, with unreliable vacuum tubes, and broken literally half the time.
From wikipedia:
http://en.wikipedia.org/wiki/ENIAC"ENIAC contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed more than 30 short tons (27 t), was roughly 8 by 3 by 100 feet (2.4 m × 0.9 m × 30 m), took up 1800 square feet (167 m2), and consumed 150 kW of power."
"Several tubes burned out almost every day, leaving it nonfunctional about half the time. Special high-reliability tubes were not available until 1948. Most of these failures, however, occurred during the warm-up and cool-down periods, when the tube heaters and cathodes were under the most thermal stress. Engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days. According to a 1989 interview with Eckert, "We had a tube fail about every two days and we could locate the problem within 15 minutes."[15] In 1954, the longest continuous period of operation without a failure was 116 hours - close to five days."
I ALWAYS do it right just because it's my work ethic - even when it's for someone else and the customer will never see this connection / weld / fastener.
Do it right. Solder the wires and shrink-wrap them. That will never fail.
