Just be wary that you don't eat too much of the tweaked foods. As you aren't using the smash as the product is intended to be used, SW say you should give it the same syn value as the product that you are replacing it with should have. So if you are using it as pastry, syn it as you would that pastry (25g of puff is 5 syns, 25g of filo if 3.5 syns)
The problem with using smash to replace things like pastry, or pizza bases, or gnocchi, is that there is the chance that you will 'overeat' that particular item and it'll be detrimental to your weight loss in the long run.
Eating it once every so often is fine, but it's like people making the lasagne sheet 'dorito' style crisps. They aren't meant to be used that way, so you should syn them as you would a packet of doritos. If you think of them as free, there's that chance that you could eat them a lot more frequent then you would an actual packet of doritos.
I know you aren't new to SW, and most likely aware of the old 'tweaks' that people have done, and some still do, I just wanted to make others aware of what SW's line is regarding the tweaks.
There will always be the age old debate that there's nothing wrong with them and they shouldn't be synned, to those that agree they should be synned etc. Whether they impact on someone's losses or not will be person specifc and based on how much thye eat of whatever the tweak is.
...Now I've rambled for England, I'll step off my soap box now