Looks fine, Perma hasten isn't as important as a defense softcap though. You can be off of perma by 5 seconds and it wouldn't be much of a difference.
But for maths sake: Hasten recharges in 450 seconds and has a 0.924s cast time (arcanatime included). Add them up and it's 450.924. To have a 100% uptime, since Hasten's duration is 120s you'd need a recharge modifier of : 450.924/120=3.757, which is +275.8%. You get that from:
1. Recharge enhancements+Alpha enhancement in Hasten.
2. IO Set bonuses (including Luck of the Gambler IO's).
3. Hasten itself.
So without Hasten itself, it's 205.8% recharge.
With Hasten and Set bonuses, assuming a 99.1% Hasten recharge (3 recharge IO's), it's a 176.7% recharge requirement, close to your 175% mark.
So 175% is a solid estimate pre-incarnate era where everyone used 3 recharge IO's. After incarnate content came out, everyone's Hasten slotting values became different. Some people had 99.1% still, others had 114% with 2 slots and agility, while others had 124.9% with 2 slots and spiritual core.
Then along came other factors, like the Ageless Destiny incarnate power and enhancement boosters (making people use two +5 recharge IO's instead of 3 regular ones).