With the plentiful bounty of granite ledges and boulders within a keels distance under the surface I believe a full keel would certainly help distribute the impact load. The best insurance is just don't hit anything. We were on vacation in the Caribbean and met a couple from Maine. Of course we ended up on the subject of sailing and unexpectedly I realized I brought up a bad subject. Long story short: They owned a sailboat and were sailing in Maine. He had to use the head and she took the helm. She ran into a rather solid rock ledge and tore a hole in the boat with the impact. The boat sank, they were rescued and the rest is another story. I always remember that story whenever I go to Maine.
Perhaps it may help "distribute the blow" but IP keels are "encapsulated" and I know at least some were filled with concrete. When you crack it it can take MONTHS for it to fully dry out before a repair can be completed. We had an IP here in Falmouth two years ago that was on the hard the entire summer and was still weeping after two months. In the meantime about 6 or 7 external lead boats were repaired and re-launched. As mentioned best not to hit a ledge!!
If you have a Hinckley, Cape Dory or other full or cut-a-way keel with external lead then hit what you want and you won't damage much except for distorting the lead some.
I would ask how the OP plans to use the boat? If coastal cruising Maine I can think of many options in the 135k price range that would be very well suited to coastal Maine sailing. We see many IP's up here motoring when other boats are ghosting along at a decent rate in under 10 knots. If you don't mind motoring in light winds then this is not an issue.
Here in Maine we can certainly see high winds, and do, but generally they are light in the summer months. Tim R. & I just did a 100+nm delivery and saw only 4 +/- hours of actual sailing and the remainder was motor sailing, and this was on a boat that will do 6 knots in 10-11 knots of wind.
Our next door neighbors owned an IP that I used to sail on quite a bit and they put a lot of hours on the engine because it did not do so well in winds under about 12 knots. It reached well in higher winds, and tracked well, but pointing ability was rather lack luster. They kept a day sailor for getting their "sailing" fix. Nice boats in high winds but certainly there will be limited sailing performance in the light summer winds we often see here in Maine. If you're not into sailing performance then they are very well built boats. I would definitely try and avoid ledges and rocks though..
Other boats to consider in that quality & price range would be a Sabre 38 MKII, Sabre 362 Fin, Tartan 372 or 3500, J-37C or J-40, Passport 40, Caliber 35 or 38, Valliant 40 and others too..
