I'm sure it would be fine... Less is beter tho... Like u say, try a lil, and see how the plants respond... Its only nutrient-based liquid fertilizer, so I dont see how it could be bad for use in soil...unless u use too much...
Using hydro nutes in soil at near full str is better than standard soil nutes for indoor as hydro nutes are designed for hid lighting, just give them a flush(ph 6.5 water) every 6th watering/feed to avoid salt build up and you wont have a yellow leaf on the plant.