Yeah but I've spent 7 years selling against their product. You think my accounts would understand if I flipped?
This was my first thought when I read your OP.
You need to figure out how you would explain to all of your accounts why buying from your new company is the right thing to do after all those years of you telling them it would be the wrong thing to do.
Were you lying to them all those years or were you just wrong all those years? Either way it would not inspire confidence in you by your existing clients.
Of course if your current company's products have declined in quality or customer support has declined, etc., and you could not continue to support them, well, maybe that would be a valid reason for you to change employers.
Otherwise, you're just going to look like a mercenary.