Playing Outside your Limits?

I'm writing this blog to try and get a little feedback about whether or not I'm risking too much of my bankroll in playing the matrix tournaments that I recently discovered on Full Tilt. For those of you that aren't familiar with the format for the matrix games, it works like this:

• 6 or 9 players buy in as if it were a regular Sit & Go game.
• This group of players plays the same format of poker at 4 different tables.
• The payouts at each table are 1/5 of what they would be for a regular single table Sit & Go.
• You earn 1 point for each player you last longer than.
• You earn 2 points for each player that you knock out.
• You earn an extra 2 points for winning one of the tables.
• After all the tables are finished, based on the amount of points that you earned you get paid as if you had finished in that position at a table.

Now, with all that being said, here is what I have done a couple of times now and I'm not sure if my logic is flawed or if I'm being sensible. I currently have around $140 in my account on Full Tilt which I have built up from scratch without any deposits. The first time I played a matrix tournament, I bought in for $1 + $0.25 and after playing for a little over an hour I ended up cashing out for a total of $1.98. After analyzing this, I realized that I could consistently make a profit by playing solid in this format but it would rarely be a large profit. So, the last couple of times that I played the matrix games, I bought in for $5 + $0.50 (well above what I should be risking with my current bankroll) and ended up cashing out for over $11 and making a decent profit. So, with the prize fund being split up 5 ways, is my thinking flawed in that playing one $5.50 matrix Sit & Go is the same as playing 5 $1.10 Sit & Gos and I'm actually well within the limits of my bankroll?

Please let me know what you think about this and whether it may be a good idea to raise the stakes a little more of if I'm putting too much at risk. Thanks.