Hi orillah,
glad you're enjoying the build
DPS calculation in this game is tricky business, as so many things come into it (attack speed, damage per swing, DR bypass, enemy's DR, accuracy vs. deflection, lashes, other abilities, ...) and there's a point past which making comparisons becomes very hard. This is one of those cases, as we're way past the point where differences ... well, make a difference. I mean, reaching 0 recovery while packing damage bonuses looks and feels cool, but you can easily beat the game with a lot less firepower—and this gives you ample room to tailor equipment choices to your preferences and play style.
Tidefall is (has always been) an impressively good weapon and is definitely still a good choice for this build, even though I didn't personally go for it.
Running a quick DPS comparison for the sake of argument:
Attack speed at 24 frames for both weapons; recovery is 0 for the BotEP, (135% - 72.5% = 62.5% * 50 = 31 / (1.36)) = 23 frames for Tidefall. Both have a 4-frame animation delay, so total attack time is 28 frames for BotEP, 51 frames for Tidefall.
Both can be enchanted with an elemental lash, which adds +25% of the total damage against 25% of the relevant elemental DR (but with Vulnerable Attack, both have a higher DR bypass than 25% of the target DR we're using in this example.)
Average DR against Pierce is 9.5; against Slash/Crush is 8 (source) so I'll use these values. Both weapons using Vulnerable Attack.
Tidefall has the Raw DoT lash as well, which I'll try to take into account.
Average damage per swing when fully buffed (MIG 37) should be as follows:
Min = 14 * (1 + 0.81 + 0.15 + 0.15 + 0.1 + 0.2 + 0.45) = 40
Max = 20 * (1 + 0.81 + 0.15 + 0.15 + 0.1 + 0.2 + 0.45) = 57
(40 + 57) / 2 = 48.5
DPS calculation assuming Accuracy = Deflection and all hits (no misses, grazes, or crits):
BotEP (10 DR Bypass)
1 attack every (28 / 30) = 0.93 seconds
Swings in 10 seconds = 10.71 (let's round it down to 10 for the sake of simplicity)
Pierce damage = 48.5 - (9.5 - 10) = 48.5
Lash damage = 48.5 * 25% = 12.1
Total = 48.5 + 12.1 = 60.6 damage per swing
DPS = 60.6 * 10 = 606
Tidefall (5 DR Bypass)
1 attack every (51 / 30) = 1.7 seconds
Swings in 10 seconds = 5.8 (let's round it up to 6 for the sake of simplicity)
Slash/Crush damage = 48.5 - (8 - 5) = 45.5
Lash damage = 45.5 * 25% = 11.4
Total = 45.5 + 11.4 = 56.9 damage per swing
DPS = 56.9 * 6 = 341.4 + Raw lash
Raw damage = 11.4 over 5 seconds
This is harder to calculate, but over 10 seconds you should be able to put through 4 full Raw lashes and two partial ones (to simplify, I'll count the latter two as 1 full Raw lash). That's 57 damage.
DPS = 341.4 + 57 = 398.4
BotEP is the clear winner, but Tidefall also heals you by 20% of the damage you deal which is pretty neat.