The Mk1 was pushed out to market presumably to start recouping R&D and set up costs.
Unfortunately, this proved to be a mistake as the rifles had many issues and FX took a lot of flack. Blackpool air rifles even stopped selling them and that says something.
Eventually, they ironed out a lot of the Mk1 Issues. The Mk2 was a game changer imho though.
Reliability seems to have improved very significantly and now distribution and customer support is via The Sportsman chain which I believe is a bigger organisation than the original supplier.
Most seem to consider the Mk2 to be the minimum requirement and now further editions and improvements are coming out as well.
If you want an accurate compact sorted rifle then the Impact Mk2 or the newer models would be an excellent choice. Some don't like the looks or the tactical design but to be frank, you are not buying a MK2 because it looks pretty. As it goes, the functionality is what I think the Mk2 is about as well as doing its job to a very high standard.
In a battle of wits I refuse to engage with an unarmed person.
To one shot one kill, you need to seek the S. Kill only comes from Skill