First of all, you will more than likely loose a lot of muscle on that plan. You're going from lifting nice #s to just about nothing. If you're getting a good burn, that's YOU, but I'd drop the weight just enough to be able to only do 15 reps, staying as heavy as you can, to keep the muscle mass you have (more lean mass burns more calories).
Second, I wouldn't recommend dropping the weight anyway. Stick with what you can do, just decrease your rest times between sets. Limit them to 30 seconds. Then see what weights you can still do, and get complete 12-15 rep sets. Also, increase your cardio, and most importantly...... DIET DIET DIET!!!! I shouldn't even call it diet, just eat cleanly.
The high reps doesn't really help in leaning out. It's the fact that you're doing more, causing the heart rate to raise, causing more calories to be burned. You're not going to look anymore striated, that's genes. That's why I say stick with the "heavy" weights, 30 seconds rest between sets, and then make sure you're doing 20-45 minutes of cardio 3 to 5 times a week. I'd tell you exactly how much to do, but I have no clue what you're doing now.
I'll tell you a little of what I've gone through in the past few months. Before the Thanksgiving/X-mas holidays, I was 220 lbs @ 12-14% Body Fat. I've changed nothing with my weight lifting routines, added some supplements, played around with my cardio, and just ate consistently and cleanly. I'm now down to a little under 200 lbs @ 4% Body Fat, with less than 2 weeks to go until my first body building contest. I'll be weighing in under 187.5 lbs for the Middleweight class.