Lots (!) of past information is available on this subject. You need to search the message archives here, and at the message archives at Sailnet.com, and at the YachtList<
http://www.xs4all.nl/~erkooi/YL/>.
The broker is telling you only a little bit of the story. Water can indeed be trapped under the sole pieces in an Ericson... and a Catalina, a Hunter, etc. etc. Remember, the broker may well be an honest person, but he/she works directly for the seller. You need a good survey, in any case.
Heck, my 1981 Niagara used an frp interior liner that had areas where the teak&holly surface plywood sole was laying on a flat frp surface... I kept the sole varnished on all sides and it looked like new after my dacade of ownership.
Depending on how Ericson attached the sole in that particular model, you may only have to remove plugs and ss screws to take the sole pieces out... or you may find that they also put some sealant down on flat frp areas to further stick it down and "keep it from squeeking" when trod upon.
On our Olson 34, constructed by Ericson in 1988, all the sole pieces were screwed down and plugged. No edge trim pieces, and no adhesive used. They were in terrible shape when we got the boat in '94. I removed them (4 major pieces) and took em to a furniture stripping place where they and the cabin table pieces were dipped/cleaned. This removed a combination of enbedded dirt and old oil. We then used "Teaka A & B" to further lighter the appearance. I plugged all the old screw holes, drilled and countersunk new holes so as to leave the heads flush with the surface. I also used teak plugs on several interesting divots. Then about 6 coats of varnish were applied to both sides. While these were out, the bilge was cleaned of old globs of glass mush left over from construction, and the the bilge pump wiring renewed. Later I gel-coated the whole bilge white.
Now, the sole sections can be removed in minutes to get at the bilge areas for maint. I finally replaced the shiny/obnoxious SS screws with bronze square-drive screws this year so that, appearance wise, they are nearly invisible against the teak surface.
This upgrade really drives up the "ohh and ahh" factor when friends visit the boat.
I did indeed contemplate replacing the sole, but in '95 the two pieces needed would have cost me at least $150./sheet. There was no rot in ours, either, just neglect and zero care.
YMMV.
Good Luck and keep us informed of your progress,
Loren