Stalwart '85 Character Advancement

I just posted about how I had to get some clutter out of the way, and suddenly I'm thinking of Stalwart '85 and character advancement... I was thinking that in the comics, characters do grow over time, but it tends to be very slow, with gradual increases in character effectiveness and power, and (once in a great while) bumps in character growth. I was thinking of something like this to tinker with for S85 and character progression...

OPTION ONE 

After every adventure, you have a cumulative 1 in 20 chance of advancing (so after the first adventure, you would have a 1 in 20 chance... after the second a 2 in 20 chance... after the third a 3 in 20 chance)... once you are successful, this resets. If after your third adventure, you roll a 2, you'd get to advance in some way, but the chances of increasing again would be reset to 1 after your next adventure. When you advance, you'd roll 1D6 to see how you advance...

1. Shift Body +1 Die

2. Shift Mind +1 Die

3. Shift Power +1 Die

4. Shift Reflex +1 Die

5. Gain one new Gift.

6. Increase Tier/Level +1.

On average, you would advance once every ten adventures, and you'd advance your tier/level once every 60 adventures. The GM would (of course) set caps on such advancement (or not. Think of Jean Grey becoming the Phoenix as an example of a character who got a pretty significant upgrade).

OPTION TWO

This is a more traditional XP progression. You earn experience points (an average adventure grants 5 xp... you earn 2 xp for an adventure that you do poorly on, but can earn up to 8 xp for a very successful adventure). You bank XP and then spend them to increase traits or tier, or to purchase new gifts.

Traits are 10x the dice value you are moving to... to shift from Might D10 to D12 costs 120 xp.

Tier are 20x the dice value you are moving to... to shift from level 4 (D8) to level 5 (D10) costs 200 xp.

New gifts have a default cost of 100 xp.