I drove a 1985 S10 since 1994 and bought a 1997 S10 new. I sold the '97 in '99, keeping my first gen until 2001 when I sold it and bought a new 2001 GMC Sierra. The full size was like a luxury liner compared to my old S10. It's almost been 10 years and I have no complaints about my full size. I did, however, miss my 1985 S10 and bought a 1987 S10 this summer.
I say sell the S10 and get a full size if you have the means. You can always sell/trade it later if you miss the smaller truck. Hopefully the S10 buyer will drop an LSx motor in it and all will be right with the world.