NIMH Batteries

Dear List,
It is time to replace one of the battery packs for my sailplane. I
currently use packs consisting of 7 2.5V SLA batteries to make a 14V
pack. This has worked very well for me in the past but the AH on these
cells is somewhat limited. I would like to ad a transponder and
possibly some type of collision avoidance device so I am looking to
upgrade the power supply. I have seen Nickel Metal Hydrate batteries
that come in 12V and 10 to 14 AH sized the same as the SLA batteries
alot of the glider people are using. There is a company in the UK ,
ATSI, who markets these NIMH batteries for aviation use. My question
is does anyone on the list have any experience with these or any other
12V NIMH batteries for glider use. I dont mind using the sealed lead
acid batteries but the NIMH has many advantages . And yea, I know
price isnt one of them.
Thanks