The Clark method is the only one I've ever done. If you can tolerate the lemon+maple+cayenne, you will find the olive oil mix easy. Even the Epsom Salts aren't so bad, just make sure you drink that stuff room temp... cold is horrible.
The lemon will be fine with the olive oil, all the fruit juice does is separate the oil and make it easier as it's going down. No doubt 1/2 cup or so of lemon juice is going to be really powerful! I have only used the grapefruit. If you got a really high quality/low acid olive oil (I hope you did) - it'll burn your throat as it goes down... very peppery stuff.
The thing people mainly notice after their first flush is a big improvement in digestion. I've had my co-workers do it (people you'd never think would even be interested) for no particular reason at all, just to cleanse, and they didn't even know their digestion could improve. I have done 7 myself, more to come soon. Just make sure you hydrate yourself well in the first part of the day and everything will be easy :)