There are mother plants of val and crypts in my original OERFUG planted tank which have never been moved and likely will not ever be moved until the tank is finally broken down somewhere beyond ten to fifteen years old. I have had no issues from this, nor do I anticipate any in the future. Don't look for problems where there are not any. This is not bonsai, it is very simple aquatic gardening. It may eventually point out a few more or the many myths associated with the use of UG in tanks as being just that, but until that time, consider the doomsday scenarios of planted tanks and RFUG at least to be unproven pipedreams quoted without data by folks with absolutely no first-hand experience, or at least no educated experience.
The forums are full of folks citing horrible outcomes on things about which they know little or nothing, in all honesty just repeating what they in turn have read. The fact that they heard no original source facts is trivial to them. I have spent many, many hours over quite a few years researching UG and RFUG on the web and in print. I have never, repeat never, found any original material where the individual used and maintained RFUG properly and had issues from plant roots. But you can find negative comments by the page full, all second-hand and unconfirmed "information". Part of my rep of being nasty comes from my asking frequenty how this "info" is known - I get nothing first-hand and factual from that - basically just that "everybody knows that". My response to such remarks would be obscene, so I drop it.
When plants are moved in any substrate, and certainly still if not more so when equipment is incorporated in that substrate ( heater cables or UG plates with or without bonded floss), there are broken roots and rootlets left behind. Ditto when plants in the garden are moved. This is normal. So long as the substrate does not become excessively organic (which can and does happen over years with conventional substrates in aquatic gardening if not compensated by vacuuming well when clumps of plants are lifted and divided, and can potentially occur almost as well with planted RFUG/OERFUG*), there is not going to be any issue.
*IMHO & IME, RFUG/OERFUG are less likely to become overly organic as so much of the soluble breakdown product is flushed from the substrate by the upward flow through it. It does not stay in place in the substrate mulm as it does in conventional substrates. Just as RFUG substrates do not become nitrate reservoirs as do conventional substrates (unplanted) in ordinary FO tanks, similarly they do not become organic material reservoirs as do undisturbed planted substrates.
HTH
