A trials bike should be set up with one thing in mind. What position should you be in to be "neutral" over the bike. How does a boxer stand, a weight lifter, a surfer or a ballerina? The neutral position is where you are able to react and move your body in order to maintain balance. If your sparring and wrestling, you will be legs bent, arms bent, ready to move left, right, up, down, laterally and diagonally and pivot. You are able to fully extend, absorb, rotate, flex and react. Try standing with your feet together and let someone push your shoulder laterally. You will take a large step in order to regain balance or fall over. Now spread your feet apart and let them push with both hands. You will extend and react to the opposing force. Maintain your balanced position.
Neutral athletic balanced stance, applies in all sports, even yard darts. So with that in mind, understand that by reducing your flexed balance position by requiring you stand taller over your center of gravity, you have made the task of balance very difficult because you gave up your balanced stance; with the risers. If you bought the trials bike to ride TRAILS, then heck yea get comfortable, otherwise it is or should be a hindrance to a balanced position. The bike goes crazy underneath you while the body maintains a neutral and quiet position. Riding in any bike is all about rhythm and flow. Got to tune the instrument to get good rhythm and you can tune a piano but you can't tune a fish......
Try it and see is the best way to find out. Self guided discovery.