One thing that might give you a bit more comfort would be a deeper roll. The 20 buyin rule tends to get grinders to tilt when they lose a couple buyins. A lot of people increase their BR requirements by level. You might consider using your winrate as a requirement. Here's the plan I set for myself about a year ago:

Code:
 limit    winrate       BIs  $
 25nl   - 5ptbb/100   - 20 - $500
 50nl   - 4ptbb/100   - 30 - $1500
 100nl  - 3ptbb/100   - 40 - $4g
 200nl  - 2.5ptbb/100 - 50 - $10g
 400nl  - 2ptbb/100   - 60 - $24g
 600nl  - 2ptbb/100   - 70 - $42g
 1000nl - 2ptbb/100   - 80 - $80g
I think spoon's increments by 5s instead of 10s, but his req. for 25nl is 25 buyins, so 50 would be the same.

Anyway, if you write up a specific plan then you move up when it tells you to. You're just following directions. It takes the pressure off and allows you to just play poker.