I raced a Mistral Superlight, F2 Lightening and Mistral Equipe XR and still have my '85 Superlight. All are great long boards, but I would not recommend any for beginners.
The Superlight is pretty tippy but super efficient in light winds (under 10 knots). The F2 and Mistral are race boards, but finding one in good condition and a working dagger board gasket will be almost impossible. Neither will be as stable the Rio, but both can be a lot of fun in light and strong winds once one achieves an intermediate sailing level (planing, tacks, jibes/gybes, foot strap use, harness use, beach starts, and possibly water starting).
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.