Advice needed on choosing a tempering machine.

I am looking for some advice on what type of tempering machine would be suitable for me and the rate of production I can expect. I have only ever tempered by hand (normally I use a bain marie.)

I am based in the UK and would like to be producing 30 - 60kg of tempered chocolate/day. I am unsure of what size machine is needed to produce this amount.

It is my understanding that a melting tank may be unsuitable to work with throughout a day due to there being no stirring function. If I was to purchase a melting tank, I would probably choose one from Keychoc. Does anybody have any experience using these?

If a melting tank is unsuitable, I have looked in to Semi-Auto temperers. Based on what research I have done, the prefamac 30kg moulding machine appears to be a good option but do I need it to be as large as that? Will a Chocovision 20kg suffice? Alternatively there is the 7kg Chocovision with the holey baffle. 

Additionally, I have a question involving "seeding". I have seen this term used in two different ways. With tempering by hand, I have used the "seeding" method before where I added 1/3 untempered and unmelted chocolate to melted chocolate in order to reduce the temperature quickly, before warming it again for it to become tempered.

However, I have also come across it in terms of using a seed to temper a large batch of untempered chocolate by adding a small amount of tempered chocolate to allow all surrounding chocolate to form the same structure and you have your entire batch now tempered. Am I understanding this correctly? For a melting tank or semi-auto temperer to produce tempered chocolate do I need to add tempered chocolate or untempered chocolate and then adjust heat as needed?

Thank you for any advice you can offer.