Sure. Battery consumption is a bit of an issue but it's also not really an issue in practice. Here is what I mean. I recently spent two weeks in the Philippines. Did 48 dives totaling over 50 hours underwater. We typically did five dives a day of at least an hour per dive. The Icon had no problem keeping up battery-wise.
Having said that, it was necessary to charge it every night while I was sleeping. It would not have lasted two days at that rate. Now during a normal dive weekend in which I'm teaching open water students it keeps up without having to charge it at all.
As for usage during storage it does slowly bleed the battery (quickly compared to most other computers) and will last a week or two. So I've just got in the habit of making sure I charge it up the day before I go diving. If the battery gets to zero (which again takes a week or two) it will reset the clock and calendar but that issue isn't happening when the computer has a charge anymore.
As for the transmitter the old firmware frequently did not report battery issues and I was constantly changing batteries at the most inopportune times. That is fixed now with the latest firmware now reporting the battery status of the transmitter.
One thing that will significantly effect the transmitter batter life is if you leave your tank attached to your regulator under pressure. If the transmitter senses pressure it will continuously report that to the computer. So once I've set up my kit and verified my pressure, I turn off my air and purge the system, until I'm ready to dive.
Since the new firmware I go through two or three transmitter batteries a year. They are user replaceable but be careful when you do it. Make sure the o-ring is intact and that you carefully replace the cap. It's not hard though.
Also, don't drop the transmitter as that can break it. Mares has been very good about covering the two times I've dropped it and broken it. As a precaution I keep an extra transmitter on hand so that my wife and I have an extra should something go wrong. So far it has just camped out in its lonely box.