A bond that is deducted from your pay = paying AND being "locked in". Hmmmm.... is this wise (why not borrow the money, pay for the conversion and keep your options open. Also, you might well find cheaper training elsewhere, given the figures they have quoted to some prospective pilots).
You really need to find out what is involved here. Remember, the offer you are talking about is completely different from that being offered elsewhere (some worse, some better). Have you read the multitude of threads here warning about the various scams used by Ryanair to get you in and then extract money from you? If not, go read them. If yes, then you have been warned.
How about this for a forecast: by November Ryanair will be offering free NG transition training with a reducing bond? They might even start to treat people reasonably (at least for while). Is a pilot shortage not a wonderful thing?