0.79% is relatively high for a mustachian portfolio - most people around these parts have overall portfolios with ERs of around 0.10 - 0.4%. But 0.79% for a "normal person portfolio" is pretty good.
Most investors in the US are walking around with junk drawer portfolios (no overall plan, no clue why certain things ended up in their accounts) with expenses of 1.2% or more, loaded funds, etc. 0.79% fees on a logically allocated, diversified portfolio, in a tax-advantaged account, is nothing to sneeze at.
The reason I suggest you just kinda be "zen" about the 0.79% fees is it sounds like that's the best you can do in your current 401(k). With 401(k) accounts, you don't have a choice of which investment firm to use: you've gotta go with whoever your employer picked. If that's Vanguard, great! If it's Morgan Stanley or someone more expensive, welp, it is what it is. Do the best you can with the choices you've got in that account. Even with fees a bit higher than you'd like, the employer match, high pre-tax contribution limits, and tax-deferral that 401(k) accounts offer still make them the best "first line of savings" for most mustachians.
My question now is, if I were to find a different fund which invests in stocks just like FFFHX, but has a lower expense ratio, should I look to switch?
Yes, but this is unlikely. Keep your eyes peeled - if your 401(k) plan adds a bunch of index funds, the odds are good you can clone the FFFHX portfolio allocation for about half the cost. Until you hear your company saying they're adding a bunch of index funds to the menu, you are likely positioned as well as you can be.
Remember that when you
leave your employer, this all changes.
Once the 401(k) company gets word that you're no longer working at the company (usually a month or a quarter after you leave), you can 'rollover' your old 401k to a Rollover IRA, where you can choose nearly anything to invest in. If you roll to a company like Vanguard, you can choose the Vanguard equivalent of the target-date fund you were using, VFIFX. That has an expense ratio of 0.18%. Alternately, if you're itching to self-allocate, you can choose a mix of index funds that add up to the asset allocation you want.