We are looking at them too for deduplication at form fill as well as cleanup all out duplicates. I am not getting many positive feedback on RingLead but i have yet to talk to someone who can provide us with details reason of why and what alternative we should be looking at instead?
Have you made any progress on this?
I had also heard of another one recommended by Marketo and another individual, called Leadonance. I haven't used them, since we didn't have the budget currently, and another alternative that Marketo pushes is their consulting sprints with using Smart Merge. Once again, I don't have a lot of info on the results or opinions, since we didn't have the budget. I've basically resorted to going in and cleaning out all the obvious "junk" and old leads and have reduced our database by about 50%!! Be sure you go for the low hanging fruit first. This will also help with lowering the cost for the deduplication, which charges by the size of your database and/or the number of leads. Most of these guys are willing to speak with you to give you a lot of free advice, so that may be worthwhile starting points. Though, the duplicates can cause all sorts of productivity problems and even syncing problems, so duplicates is definitely not something to ignore. There is also a package that our company already has their software, called Cloudingo, but we don't own the Enterprise edition, which can deduplicate across both Marketo and Salesforce.