My work investment options were always limited to mutual funds and the options have been fairly good these last few years. I always figured that the mutual funds were the safe part of the household's portfolio. They've actually done well, and they tend to be very good, reputable fund companies, so lucky in that respect.
In hindsight, though, if I had pulled them out at age 59-1/2 y.o., as was allowed, and managed it like other stock/etf investments, I would have done appreciably better. But no complaints, and they were and are doing well on ROI.
On the other hand, I left one employer in 2000 and rolled over my investment into a self-directed IRA, bought stocks, and it readily outperformed anything I would have done if left in mutual funds. GOOGL is the big one there, and the rest were and are tech.
As for your choice going forward, a 5% fixed rate is nothing to scoff at. I'd look seriously at that, as long as the company looks to remain solvent. I mean, I get excited about a variable interest rate at just under 5%, and that is not fixed.
on another note: How about that Amazon?!