I'm in exactly the same boat, except my money is sitting in equity in properties ($3.1M in equity on $4.4M of investment property, another $1.1M in equity on my primary residence. And I'm basically thinking the same thing. Can't beat the returns of syndications if you're looking for passive income. I'll be tapping into it via leverage, but not borrowing past the cash flow from the properties.
But I wouldn't bank on the exit at the end of 5 years. To @Todd Dexheimer's point, the exit is a big piece of your math, and if the timing isn't right to exit, you don't want to be banking on the exit. Smart syndicators won't be forced to sell because of the way they've structured the deal. So, don't spend the money from the exit until you have it... aka live below your means and everything on top will be gravy.
Also, if you have $500k in cash now, I wouldn't worry about staggering the investments. In reality, if you invest in 5 different deals (presumably across multiple syndicators) and you do them all at the exact same time, you'll probably exit at least 3-4 of them in different years. And that's a good thing...you don't want 5 deals all exiting at the same time, your tax hit would be absurd.