"We know that advisors drive this market place," said DeSilva, bluntly.

What is also known? Recordkeeping fees are at an all-time low, according to NEPC.

A recent study from the Boston-based consultancy puts the median recordkeeping fee in 2015 at $64 per participant, down from $70 last year, and a precipitous decline from the average of $118 per participant in 2006.

That's clearly a win for participants, and likely a competitive motivator for recordkeepers to more aggressively court RIA plan-specialists.

But as they knock on RIA doors with new product innovations, one study from Cogent suggests advisors may not be answering.

In this year's Retirement Plan Advisor Trends report, Cogent, the financial services research arm of Market Strategies International, shows that plan specialists are only recommending an average of 2.4 plan providers to sponsor clients.

And one-third recommends only one provider.

All told, advisors work with an average of 2.7 providers for their entire book of DC business, according to Cogent.

The safe bet is that record keepers won't be growing balance sheets with fee increases any time soon. Central to growth will be delivering more services—and all of that innovation—to more participants.

That will be hard to do without RIAs' faith in those innovations.

Plan advisors' limited use of "go-to" providers suggests they might not be buying in, at least not yet. The question for the recordkeeping industry is why.

Perhaps more time is needed for them to better understand the new products and capabilities, suggests Linda York, vice president of syndicated research at Market Strategies International, who led the research for Cogent's plan advisor report.

"I think advisors are waiting for some of this innovation to be proven, and waiting for potential bugs to be worked out," said York.

"RIAs are on the front line. The trend of innovation is a great development, but with all of these new bells and whistles, there is the risk that something could go wrong," said York.

And if it does, that falls on the advisors to plans, she added.

"I think RIAs are erring on the side of caution. The defined contribution market can and does shift quickly. The safe bet is to continue to work with the recordkeepers that have already proven they're going to do a good job."

York expects that eventually the wave of new technology and product innovations will further trickle down to more participants and sponsors.

"All of these advances will continue to bring the type of customized services to participants in any plan size that not long ago were only available to the largest plans," added York.

Like other industry watchers, she expects the innovations to continue.

Exactly which ones will be adopted remains to be seen, she added.