I dislike the multiplier because it skews the impact of starts/pt, which makes it impossible for you to win an expensive battle w/o using starts, should your opponent does.
Let's say your multiplier for Start + 20min is +30%, in an 80 CV battle (which I have seen quite a bit in Phelan), the team that offers his gains an additional 24 CV. The other team has little chance of winning this battle unless he matches under your system. With a straight 15 CV for Start + 20min (or 12, or 10 CV), you can still win a battle w/o offering start/pt should your opponent choose to do so.
Meanwhile, for cheaper battles, the effect is much smaller and makes it relatively easier for a team to win a battle w/o offering starts while his opponent does.
Logically, shouldn't this be the opposite, where playing time and start matters more in cheaper battles than in expensive battles?