Yes, what Jan wrote up for his website a good while ago is time-proven aquarist knowledge and is still widely used (I can't remember any visit at his place without noticing some crypt floating in his show tank and same-o with many other famous crypt growers over here). Mind though that this method comes from the days where mainly crypts of the Sri Lankan beckettii group and the crispatula group with a few sturdy cordata or possibly an affinis were grown in tanks filled with tapwater. Throw in a hudoroi in a tank with soft tapwater or a pallidinervia and you'll be lucky if they are not gone in short time. A tank for crypts from Bornean peatswamp forests shouldn't have any snails - if they survive, the growing conditions are just not optimal (for these crypts).
Also, not all snails are born equal - some only clean up rotten tissue while others are grateful to feast on the whole salad bar...
I've always like Physa
spp. - in my experience very gentle on live plants and a good addition to any tapwater tank ecosystem. As with any species be careful not to release them since they could be non-indigenous and invasive. Caridina
shrimp also like to clean rotting plant tissue. As do some fish.
For newly arriving, damaged crypts I usually prefer the DI water approach though (except for hardwater crypts).