The calculation is more complex with Regen x Aspected Benefic:

Regen: HoT spell. 150p for 21 seconds (7t, 1050 combined).
A. Benefic: 190 heal + 100p for 18 seconds (6t, 790 combined).

There's a difference of 260 potency, but the spells work differently.
Regen:

150 + 150 (300) + 150 (450) + 150 (600) + ... + 150 (1050).

It's a spell that works in a straight line, healing for the same amount for its entire duration.
A. Benefic has the instant healing of 190 and a 100 tick within the first 3s, which means that you get 290 potency healing done in the same time Regen does 150. Like this:

290 [190+100] + 100 (390) + 100 (490) + 100 (590) + 100 (690) + 100 (790).

This means that, for the first half of it's duration, Aspected Benefic does over 60% of it's total healing, while Regen does less than 50%. This is the reason why Regen is not a viable emergency healing spell, while Aspected Benefic can heal one target for about the same as Assize in the first 3 seconds.