Hi Gismonikon,
Actually i can see the valid points from both sides.
There is a concern that intentional cross-breeding will result in a decline of pure lines of axolotls and tiger salamanders and therefore 'contaminate' the gene pools. Releasing of such hybrids into the wild would also affect the ecosystem as hybrids tend to have hybrid vigour and would outdo pure axies, competing with them for food, more resistant to disease etc. Research involving axolotls can also become confoundered with external variables such as impact of tiger salamander genes.
However, cross-breeding can also bring forth new findings, by introducing new genes into the very limited in-breeding axolotl gene pool. New colour variants, hybrid vigour, improved resistance or feed conversion rates etc can result. If the F1 progeny are crossed back to axolotls and subsquent progeny again backcrossed, the axolotl line can become 'purer' again, while at the same time selecting for desirable traits.
Therefore i i am a quite a fence sitter on this one. I think controlled research with defined hypothesis, outcomes, evaluations and of course with valid objectives will be interesting and can be scientifically rewarding but inexperienced amateur endeavours (especially with the intent for mass sale) would most likely be detrimental.
Cheers