According to the World Field Target Federation rule 1.4 no other equipment may be used than the ones mentioned in rule 1.4. ( http://www.world-field-target-federation.com/core-rules
The digital sidewheel is not mentioned and to me it seems that this means it is not allowed to use it in matches organized under WFTF rules.
In my humble opinion we (or the BFTA and WFTF) should stop the ratrace for more equipment and stick to rule 1.4 and allow no other equipment.
I also think we should ban olympic or ISSF style shooting jackets from FT shooting. The ISSF is very busy to stop the ever increasing stiffness of coats and pants. The shooters are protesting, but almost every year the ISSF rules go toward less thicknes and stiffness. More in the direction of normal clothing.
To keep our sport fit for the future and accessible to more shooters we should aim to reduce the cost and amount of equipment used. The increasing popularity of HFT shows that many shooters are not aiming on loads of gadgets and equipment.
To keep a level playing field for FT shooters not able or willing to spend a lot off money it would be wise to reduce the costs to be spent on additional equipment like olympic/ISSF style shooting coats.