But also note that you will not be able to book the difference as a loss. I am not 100% sure but i think going forward you will have to pay tax from purchase price. So if poor performing scheme is say in 1L loss from grandfathered price and you sell now then that loss is permanent and will not be adjusted against new scheme.
Also, since you are switching within fund house, its possible that you are trying to move to best performing schemes in recent years. That may or may not work, as market cycles keep changing. Value funds are beaten down with only some stocks and some sectors making money. That wont last forever. ( As long as the old fund is decent and not say a sector specific fund or you have some other valid reason)