I'm a member of Elite and I also have shares in a few Owners Group horses (including Pentland Hills

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With Elite I pay a flat fee (first year is £199 but goes down each year with loyalty bonus and if lucky a share of prize money). For that I get at least 10 horses in training (currently horses with the likes of James Fanshawe, Sir Mark Prescott, Nicky Henderson, Alan King etc). A magazine every 2 weeks with an email report the intervening week. Access to website which provides info and regular video reports of club horses and race reports. The Club also organises visits to the races, stable visits and other related visits. I've always managed to get on the visits I want to go on - for example a couple of years ago there were visits to the Newmarket trainers over 2 days in June - day 1 SMP in the morning and Dalham Hall in the afternoon, day 2 James F in the morning and races at Newmarket in the afternoon. A two day visit like this suits me as it makes it worthwhile me taking time off work. You do have to apply to go in a ballot if one of the horses is running for a paddock place. IN addition there is a breeding programme with currently 10 broodmares (9 foals due next year) and its nice to see the foals progress and hopefully make it to the racecourse. Its fair to say the majority do make it to the racecourse and with few exceptions they win (at various levels). I'd say Elite are more flat orientated than NH. With Elite the Club owns the horses - there are no shares like a syndicate.
With Owners Group (same parent company as Elite) you buy a share (or shares) in a particular horse. There is always the chance that the horse does not race or has its career cut short due to injury etc. My share in Pentland Hills cost me £57 as I was in at the start. At renewal this year it was £46 as I had paid my share of the capital cost of the horse. Any shares that became available this year cost £166 as his capital value had increased. As an owner I get a monthly magazine, access to the website, weekly email report and the chance to apply for tickets. Again they also have stable visits etc. The majority of the horses in the OG syndicates are NH (Nicky Henderson and Paul Nichols train several other trainers include Donald McCain and Iain Jardine). The syndicates are divided into shares (usually between 3000 or 4000 per horse). I've not been on any of their visits but hopefully next year I will get to go to Iain Jardine's as I have a share in a horse with him and its the closest OG yard to me.
Hope this helps. At the end of the day it depends what you want from a share/club and how much you want to spend.