Why Update To EMV?
The main reason to update to using EMV is to reduce your liability in the event of a charge using a counterfeit card. However, there are other reasons to move to the new device - you'll get support for contactless payments, and if you are not presently doing debit transactions the VX805 device also allows for the support of that.
If you upgrade, you will no longer have a use for your old MSR or, if you have one, your old 1000SE PIN pad. The VX805 unit includes more secure versions of both of these.
If you do not want to update to EMV and are using integrated payments within ExtremePOS, Musicware, or Praiz, then your existing solution of ExtremePOS Payment or TransSentry will continue to work for the immediate future. However, you will face increased risk, being liable for any charges where a chip card could have been used as EMV and that would have prevented the fraud.
While this update is not currently mandatory for integrated payment users, the urgency of it depends on your comfort with shouldering the risk of fraudulent transactions. This is something each merchant has to decide for themselves.