which new mira shower to buy

[sajjed]

hi,would be grateful for advice.i am looking to replace my trevitherm shower have had excellent use of it for 13 years but have decided to replace shower cubicle so think its time to replace it.
i am looking at mira excel or mira discovery,there is quite a difference in price so wondered it anyone has an opinion on either of these. thanks

 

[sajjed]

have trawled the local shops cant find stockists of these mira showers so if i go ahead and buy it will be by ordering it.
would appreciate if anyone can explain to me the following.
excel has 4.8 litre flow rate so i guess this is more economical than the discovery 10 litre flow rate, does this mean the excel is not as powerful a shower when in use?
discovery says concentric flow the excel says seperate flow. i havnt a clue what this means either, i would be grateful for any advice please.