I considered the S420 to be slightly underpowered, but an excellent smooth ride to cruise in. DIY friendly? Yes. The diagnostics are really a breeze. You also avert wiring harness issues with 1997 being the year that the wiring wasn't bio-degradable garbage anymore. Also, all Mercedes models received the 722.6 in production in 1997 and they aren't really prone to catastrophic failure like its previous predecessor. A lot of good examples out there so shouldn't be hard to find one in good shape.