If im reading it right, you are currently receiving CH61 disability pay minus VA offset pay, but have a 20 NG/reserve retirement letter. If you are not age 60 and collecting CMRP (concurrent military retirement pay), then yes you are leaving some money on the table by not applying for CRSC.
Info you provided:
High 3 from ERAS = 6467
CH61 DoD 70% = 4526.9
VA 100% = 4413.63
Reserve Pts
2995 / 360 = 8.32 x 2.5 = 20.8% multiplier for longevity
$6467 x 20.8% = 1,345.14 longevity portion of retirement ( Ceiling for CRSC and your CMRP pay at age 60)
4526.9 DoD retirement reduced by 4413.63 VA comp = 113.27 residual pay
So current pay is 2 paychecks
1. DoD Ch61 = 113.27
2. VA pay = 4413.63
If you apply for CRSC and get approved, you would need a CRSC% that has a payout higher than 1345.14 which is your earned retirement pension. Looking at current rates, you would just need 60% to make sure it is higher than your longevity.
Using Combat PTSD @ 70% as the basis of your CRSC claim.
70% VA rate for vet + spouse = 2,018.19 (which is higher than 1345 longevity)
I didn't use the children in the CRSC VA pay rate, as they would drop off at some point when they hit age 18.
CRSC pay would be:
1345.14 - 113.27 ch 61 residual = $ 1,231.87 max payout of CRSC
So you would end up getting 3 checks at end of month all tax free:
1. DoD Ch61 = 113.27
2. VA pay = 4413.63
3. CRSC = 1231.87