With profits pension - transfer?

Apologies in advance for the long post. The executive summary is that I am wondering whether to transfer an old with profits pension into my SIPP.

I already have an auto enrolment pension with Capita that I am paying into from my current job, and a SIPP with HL that I pay some extra money into every month, as the Capita scheme is not very flexible. These two pensions I understand reasonably well and am happy with. I am at least 25 years away from retirement.

AEGON have occasionally been writing to me for the last couple of years about a Scottish Equitable Group Personal Pension plan that I paid into for less than a year in 2000/2001 while I worked at a company that I think is now defunct. While I was working there a financial advisor came in and sold everybody a pension plan and I will confess that at the time I paid little attention to what was being said. I don't seem to be able to find any paperwork relating to it now. I left that company around the middle of 2001 and stopped paying into the pension then. I put off doing anything about the letters from AEGON because I figured the pot would have at most about £1000 in it. A few days ago I finally got around to using the activation code they sent me in one of the letters and to my great surprise the AEGON website shows that the pension has a transfer value of £17076.94 as of today. It also shows total contributions of £7878.56.

I was at a loss to explain how I contributed that much money over a short period of time so I compiled a spreadsheet of the entire transaction history and it indeed shows 9 contributions totalling £876.71 gross (£846.29 net), ending on 2/5/2001. This sounds about right. However there are then 8 "contracted out rebates" totalling £7001.85 at irregular intervals from 1/3/2002 to 2/7/2012. I have no idea what these are and I am sure I did not work for the company during that time. In addition, on the 3rd of August every year there is a "Fund charge rebate", these total £252.34 and on the same day every year there is a charge entry, these total -£213.98.

Looking through the documents on the website further there is an asset allocation for the investment of contributions - European Tactical 20%, International 50%, Technology 20% and UK Equity Tactical 10%. I vaguely remember the advisor talking at length about this. Then there is a bit about a former protected rights portion and a non-protected rights portion which I don't really understand, and then there is a Plan Valuation showing the funds that the money is invested in. These first 4 funds correspond to the earlier asset allocation totalling £1454.56. Then there is a "High Equity WP fund" valued at £8273.79, and a Final Bonus of £7348.59. This adds up to the £17079.94 total.

I have attempted to research this High Equity WP fund online and have not really learned very much, other than that it seems to be a with-profits fund that is closed to new business. It also seems that the final bonus may or may not be paid, and also a Market Value Reduction may or may not be subtracted if I transfer the money out. None of the documentation seems to be any more specific than that. I know virtually nothing about with-profits pensions except that they are apparently obsolete and I am also rather hazy about contracting-out, except that I remember the advisor telling me it would be a good idea to contract out at the time. I am fairly sure I was not contracted out in the jobs I worked in after this one and my national insurance record on gov.uk seems to back that up.

So what I would like to find out is whether it would be a good idea to apply for a transfer of the money in this scheme into my SIPP, and if I did transfer, how likely would I be to get the full amount, given that the final bonus and the MVR seem to be at the discretion of AEGON? Thanks for your time.