I had to answer yes:
May 10, 2005 After-dark tornado north of York, NE
May 13, 2005 Rain-wrapped Tornado north of Benjamin, TX
I relied on it too much on May 12, 2005 chasing a small cell in Oklahoma while all the action took place in the South Plains, TX area. I wish I had had it on May 12, 2004. I would have probably punched through the rain curtain of the northern cell to get to the Harper County, KS cell.
Some Cons:
1. Mike's right about the lack of detailed visible radar features. The subtle features just don't appear.
2. The true hail core is often difficult to discern, as very heavy precip with no hail will trigger the highest color level (purple - sorry, I don't know the dB specs.)
3. The images are sometimes delayed "real-time" sinificantly. You definitely have to use your eyes for verification. Of course you should always do that anyway, but it's easy to lean back on the technology and fool yourself.
4. The equipment is expensive when considering the data you get.
5. No storm relative mean radial velocity scans. The shear markers are helpful, but only to a point. I much prefer a graphic inbound/outbound signature for location and verification.
6. The feed is a continous loop. Only the most recent data is broadcast, so several scans have to be received before any animation can be viewed. If the connection is cut off or lost, any data that is broadcast during the down time will be missing from what is stored locally, so the animation skips. And if the application is restarted, the animation sequencing usually begins all over again with the newest data.
Some Pros:
1. One-time expense for the equipment. If put to good use, it could "earn its keep", so to speak, over time. The subscription can be purchased month-to-month - no contract.
2. The data goes wherever you do - no dead zones in the plains.
3. Once receiving, the data stream is relatively quick.
4. The radar is not the only useful tool. Many suface obs can be displayed, as well as wind plots at various altitudes and echo tops for convection location.
5. T-storm and Tornado Warnings appear in real time graphically by county.
6. You can "see" the storms after dark, wherever you happen to be.
7. It becomes a safety tool when caught in a tight situation. The GPS feature allows the chaser to plot the vehicle relative to the radar imagery along with the road network. I know this feature exists on most of the other software packages, but again, the XM signal is available everywhere.
8. The above feature also allows the chaser to sometimes make better road choices when timing is tight. Delorme is great, but when you can see radar echos relative to vehicle position with user-defined distance rings and most of the important road network ahead, sometimes navigation is easier with Wx Worx.
Without Wx Worx, I have missed out on some storms, and with it, I have at times ignored my instincts and again missed out on some storms.
Bottom line: It's another tool. I certainly wouldn't REPLACE my other tools with Wx Worx, but after chasing with it for the past two years, I'd pay twice what I originally paid for it at least.