I've made several updates the to RFXtrx plugin. They are:
1) I've improved the data provided by the rain gauge code. It now keeps track of the amount of rainfall measured of the last 60 minutes, the last 24 hours, the last 7 days, the last 7 weeks and months. The values are displayed in inches or millimeters. NOTICE: Be aware that if you look at the data in the Advanced -> Variables tab, it is always in millimeters. Conversion to inches if required is done automatically by the display code. Note that if you want to set notifications you must enter values in millimeters.
2) The rain gauge code now handles the LaCrosse TX5 sensors though I doubt many of these are in use. If you are using a Lacrosse TX5 be sure that the Vera hub consistantly gets the signal from the sensor. The sensor sends a count that wraps around every 16 counts. If it's raining hard and the signal is not received before the count wraps around then the rain data will not be accurate.
3) If your particular model rain gause does not report a rain rate, the plugin will attempt to calculate a rain rate based on consecutive readings.
4) I've tested the rain gauge functionality with both the LaCrosse TX5 and the Oregon Scientific PCR800 and I believe the data to be accurate.
5) If you want to have a more appropriate graphic for a rain gauge I'd suggest searching for one online. I found one at icons8.com. If you find one, rename it to rain-gauge.png (so the name matches that in the static json file) and the copy it to /overlay/www/cmh/skins/default/img/devices/device_states
6) I've made a number of code changes to improve performance but these will probably not be noticeable.
7) I've recreated the RFXtrx Settings tab. This is the one where the receiving protocols are selected and set. My previous versions of the plugin actually had 5 different static JSON files. There was one for each type of firmware and one that displayed all the protocols even though some protocols are not available in all firmware types. If you choose to upgrade to this new version of the plugin, you may want to delete the unused JSON files. This is easily done if you're using WINSCP. It can also be done if you use PuTTY to log into your Vera. The files that can be deleted are:
/etc/cmh-ludl/D_RFXtrxType1.json.lzo
/etc/cmh-ludl/D_RFXtrxType2.json.lzo
/etc/cmh-ludl/D_RFXtrxExt.json.lzo
/etc/cmh-ludl/D_RFXtrxExt2.json.lzo
/overlay/etc/cmh-ludl/D_RFXtrxType1.json.lzo
/overlay/etc/cmh-ludl/D_RFXtrxType2.json.lzo
/overlay/etc/cmh-ludl/D_RFXtrxExt.json.lzo
/overlay/etc/cmh-ludl/D_RFXtrxExt2.json.lzo
It won't do any harm to leave these files in place if you don't want to bother removing them.

The plugin can now control a Sonoff smart switch. Not all Sonoff switches include 433Mhz operation in addition to Wi-Fi. The plugin will only work with ones that do. To add one go to the New Device tab of the RFXtrx transceiver. Select the Sonoff Smart Switch. Enter a name and any ID you want within the displayed range. Then click Create. Once the new device appears on the Vera devices page, initiate pairing at the Sonoff switch and press the Toggle button on the Vera device display. You may have to do this a couple of times. Be aware that control of these Sonoff switches is open-loop. There is no feedback from the Sonoff switch to Vera to confirm its state. The Sonoff switch only responds to one command and that command toggles its state from on to off or off to on.
The attached ZIP file contains all the files for the plugin. 4 old files have been removed, 7 files have been modified and 2 new files have been added. I've done a good bit of testing but you should be sure to have a copy of all the files you're currently using before uploading the new ones.
Update: the attached zip file has been modified to fix an error. If you've updated to version 1.40 get this zip file and upload only I_RFXtrx.xml and L_RFXtrx.lua.