There are many benefits to flashing roms. You normally get a huge performance boost as well as a boost in battery life for starters. Most roms also include long lists of custom features that aren't included in the stock experience. From time to time the addition of some features will result in the malfunction of others. This doesn't always happen but when it does it is always nice to see a developer jump on the issue and release a fix. The ViperOne rom happens to be one of the most popular roms for the HTC One M8 the only issue that has been spotted in this rom is improper sms size. For most people this is a non issue. Developer "JWhetstone02" has released a mod that fixes the sms size and also adds group text messaging, and visual voice mail on the ViperOne rom. Head to the link below for the download. It should be noted that the installation of this mod does require the use of ADB.
Via XDA