Many players have taken the path of adding more tables instead of moving up. This has gotten so popular that some players skip learning to beat the games first, and start 9-tabling as losing players. That usually doesn't end well.
Even the top player sacrifice ROI to play so many tables. You time out on the nuts, you overlook that someone raised in front of you, or that there was a microstack, you don't bother to drill down into your advanced HUD statistics, and some people even lose track of a table and blind off. In addition, most players find that they do not learn as much when they play as many tables as they can. If you are playing professionally already, then your main concern should be getting in the table-hours with your decent ROI. However, many players should have learning as a higher priority. As you are trying to learn how to handle situations and are trying to interpret your opponents' actions, don't play the maximum number of tables that you can. When you learn, you can have a higher ROI on the same number of tables, or the same ROI on more tables, or the same ROI on the same number of tables at higher stakes, whatever you prefer.
Sippin_Criss is a friend of mine. I think he would win more if he moved up, and he has taken quite a few shots at higher levels. However, it is also the case that the achievable ROI drops as you move up, and the $16 turbos have a large supply of casual players and bad regs whose games Sippin_Criss understands remarkably well*. A set loads very rapidly, even if you want to play more than 20 tournaments at once. So, while I think staying at the $16s is a mistake for him, it is not as large of a mistake as it might appear at first.
* In one triple commentary session (which will probably not ever be released), I had the mouse with about 8 players left. A reg limped in early position, the button shoved for 10 bb, and I called in the SB with AKs without waiting for the other coaches to confirm my decision. Sippin_Criss said, "No! That reg only limps high pocket pairs, QQ+!" before his KK was flipped over. That type of read, combined with dedicated study with SNG Wizard, is part of why he is the only player I know in those games whose 95% confidence interval is entirely above a 10% ROI. That is, in case his results are just because he was as lucky as he would get 1 time in 40, his ROI should still be over 10%. Many players have an ROI over 10% briefly, but probably got lucky to do so.