in typical circumstances, a peer will only announce to you their own IPs - generally transit IP is not allowed and filtered out - so I dont know where you are getting the 150,000 routes. Unless of course you have an agreement with them to allow transit IP traffic - then this case this is not peering.
Another thing to consider with peering is that they may not decide to peer with you (various reasons)
are you trying to get full internet routing without having to buy service from an upstream provider?
im not familiar with LINX's setup but just from reading their web ..it looks like a typical IXP but you still have to negotiate your peering with other providers to get access to their network - i did not see anything about transit IP routing at their page. You can always set a higher localpref on your cheaper provider to force traffic on them (inbound will be a different beast) - I typically set my localpref to 110 on the peers and 90 on my upstream
This is, as you say, a typical IXP. You will not get 150k routes just by joining. There are a large number of routes available on the MLP service, however not all members participate (we don't, for example, as our policy does not allow for it).
You could always look at partial transit which some networks in the UK provide.
Goscomb Technologies Limited - www.goscomb.net / AS39326
E: [email protected] P: +44 (0) 203 129 4400 F: +44 (0) 203 129 4410
IP Transit :: Colocation :: Dedicated Servers :: Leased Lines :: DSL
Registered in England and Wales No. 05672987 - VAT Registration No. 853 7954 80